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2019-19-10 THE BOEING COMPANY:
Amendment 39-19746; Docket No. FAA-2017-1024; Product Identifier 2017-NM-065-AD.

(a) EFFECTIVE DATE

    This AD is effective January 16, 2020.

(b) AFFECTED ADS

    This  AD  affects  AD  88-21-03 R1,  Amendment  39-6077  (53 FR 46605,
    November 18, 1988) ("AD 88-21-03 R1").

(c) APPLICABILITY

    This AD applies to all  The Boeing Company airplanes,  certificated in
    any category, identified in paragraphs (c)(1) through (5) of this AD.

(1) Model  737-300, -400, -500, -600, -700, -700C, -800, -900,  and -900ER
    series airplanes.

(2) Model 757-200, -200PF, -200CB, and -300 series airplanes.

(3) Model 767-200, -300, -300F, and -400ER series airplanes.

(4) Model 777-200, -200LR, -300, -300ER, and -777F series airplanes.

(5) Model 787-8 and 787-9 airplanes.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 28; Fuel.

(e) UNSAFE CONDITION

    This AD was  prompted by reports  of fuel crossfeed  valves failing to
    open  when activated  during flight.  The FAA  is issuing  this AD  to
    prevent an airplane  from being dispatched  on an extended  operations
    (ETOPS) flight with  a single fuel  crossfeed valve (due  to design or
    due to minimum equipment list (MEL) dispatch of a dual crossfeed valve
    equipped airplane with one crossfeed valve inoperative) that cannot be
    opened or a  fuel balancing system  that cannot properly  operate when
    activated.  This  condition could  cause  the fuel  in  the main  tank
    associated with  a failed  engine to  be unavailable  to the remaining
    operative  engine,  potentially  resulting  in  a  forced  off-airport
    landing due to exhaustion of the remaining usable fuel and  consequent
    loss of all engine thrust.

(f) COMPLIANCE

    Comply  with this  AD within  the compliance  times specified,  unless
    already done.

(g) AFM REVISIONS  FOR MODEL 737 AIRPLANES EQUIPPED  WITH  A  SINGLE  FUEL
    CROSSFEED VALVE

    For airplanes  identified in paragraph (c)(1)  of this AD:  Within 120
    days after the effective date of this AD,  do the actions specified in
    paragraphs (g)(1) and (2) of this AD.

(1) Revise the "Extended Range Operations"  subsection of the "Fuel System
    Limitations" section of the  Section 1 Certificate Limitations  of the
    existing airplane flight manual (AFM) by incorporating the information
    specified in figure 1 to paragraph (g)(1) of this AD. This may be done
    by inserting a copy of this AD into the existing AFM. When a statement
    identical to that in figure 1 to paragraph (g)(1) of this AD has  been
    included in the  "Extended Range Operations"  subsection of the  "Fuel
    System Limitations" section of  the Section 1 Certificate  Limitations
    of the general  revisions of the  existing AFM, the  general revisions
    may be inserted into the existing AFM, and the copy of this AD may  be
    removed from the existing AFM.

       FIGURE 1 TO PARAGRAPH (G)(1) – MODEL 737 AFM SECTION 1 REVISION    
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check  for  Airplanes  with  a Single
    Crossfeed Valve (Required by AD 2019-19-10)

    Prior to each extended operations (ETOPS) flight, an operational check
    of the fuel crossfeed valve must be performed. This check must be per-
    formed by the flight crew prior to each ETOPS flight  as  part  of the
    pre-flight procedure  for each specific extended range flight,  or  by
    the maintenance crew no earlier than one hour prior to the flight crew
    boarding the aircraft for the purpose of flight.
    ______________________________________________________________________

(2) Revise the "Extended Range Operations" section of the Section 3 Normal
    Procedures of the existing AFM by incorporating the information speci-
    fied in figure 2 to paragraph (g)(2)  of this AD. This may be done  by
    inserting a copy of this AD into the  existing AFM.  When a  statement
    identical to that in figure 2 to paragraph (g)(2) of this AD has  been
    included  in  the "Extended  Range  Operations" section  of  Section 3
    Normal Procedures of  the existing AFM,  the general revisions  may be
    inserted into the existing AFM, and the copy of this AD may be removed
    from the existing AFM.

       FIGURE 2 TO PARAGRAPH (G)(2) – MODEL 737 AFM SECTION 3 REVISION    
    ______________________________________________________________________
    Extended Range Operations (Required by AD 2019-19-10)

    Fuel Crossfeed Valve Operational Check

    Unless accomplished  by maintenance personnel as part of preparing the
    airplane for the specific ETOPS flight,  do the following steps on the
    ground prior to engine start.

    Crossfeed selector.......Open
    Verify that the VALVE OPEN light illuminates bright, then dim

    Crossfeed selector.......Closed
    Verify that the VALVE OPEN light illuminates bright, then extinguishes
     ______________________________________________________________________

(h) AFM  REVISIONS  FOR MODEL 757 AIRPLANES EQUIPPED  WITH  A  SINGLE FUEL
    CROSSFEED VALVE

    For airplanes  identified  in  paragraph (c)(2) of this AD having line
    numbers 1  through 518  inclusive, on  which the  actions specified in
    Boeing  Service  Bulletin  757-28-0029  (second  fuel  crossfeed valve
    installation) have not been done: Within 120 days after the  effective
    date of this AD, do the actions specified in paragraphs (h)(1) and (2)
    of this AD. For Model  757 airplanes identified in this  paragraph, if
    the actions specified in Boeing Service Bulletin 757-28-0029 have been
    done,  the actions specified in  this paragraph are no longer required
    for that airplane and the  actions specified in paragraph (j)  of this
    AD must be done before  further flight after the actions  specified in
    Boeing Service Bulletin 757-28-0029 have been performed.

(1) Revise  the  "Extended Range Operations"  section  of  the  Section  1
    Certificate  Limitations  of  the existing  AFM  by  incorporating the
    information specified  in figure  3 to  paragraph (h)(1).  This may be
    done by  inserting a  copy of  this AD  into the  existing AFM. When a
    statement identical to that in figure 3 to paragraph (h)(1) of this AD
    has been included  in the "Extended Range Operations" section  of  the
    Section  1 Certificate  Limitations of  the general  revisions of  the
    existing AFM, the general revisions may be inserted into the  existing
    AFM, and the copy of this AD may be removed from the existing AFM.

       FIGURE 3 TO PARAGRAPH (H)(1) – MODEL 757 AFM SECTION 1 REVISION    
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check  for Airplanes  with  a  Single
    Crossfeed Valve (Required by AD 2019-19-10)

    Prior to each extended operations (ETOPS) flight, an operational check
    of the fuel crossfeed valve must be performed. This check must be per-
    formed by the flight crew prior to each ETOPS flight  as  part  of the
    pre-flight procedure  for each specific extended range flight,  or  by
    the maintenance crew no earlier than one hour prior to the flight crew
    boarding the airplane for the purpose of flight.
    ______________________________________________________________________

(2) Revise  the  "Extended Range Operations"  section  of Section 3 Normal
    Procedures of the existing AFM by incorporating the information speci-
    fied in figure 4 to paragraph (h)(2)  of this AD. This may be done  by
    inserting a copy of  this AD into the  existing AFM. When a  statement
    identical to that in figure 4 to paragraph (h)(2) of this AD has  been
    included  in  the "Extended  Range  Operations" section  of  Section 3
    Normal Procedures of  the existing AFM,  the general revisions  may be
    inserted into the existing AFM, and the copy of this AD may be removed
    from the existing AFM.

       FIGURE 4 TO PARAGRAPH (H)(2) – MODEL 757 AFM SECTION 3 REVISION    
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check (Required by AD 2019-19-10)

    Unless accomplished by maintenance personnel  as part of preparing the
    airplane for the specific ETOPS flight,  do the following steps on the
    ground prior to engine start.

    Crossfeed selector.......ON
    Verify that the VALVE light illuminates, then extinguishes

    Crossfeed selector.......OFF
    Verify that the VALVE light illuminates, then extinguishes

    If the VALVE light is inoperative,  it is acceptable  to  have  ground
    personnel verify  by direct observation the opening and closing of the
    crossfeed valve during this procedure.
    ______________________________________________________________________

(i) AFM  REVISIONS  FOR  MODEL 767 AIRPLANES  EQUIPPED  WITH A SINGLE FUEL
    CROSSFEED VALVE

    For  airplanes  identified  in paragraph (c)(3) of this AD having line
    numbers 1  through 430  inclusive on  which the  actions specified  in
    Boeing  Service  Bulletin  767-28-0034  (second  fuel  crossfeed valve
    installation) have not been done as of the effective date of this  AD:
    Within 120 days after  the effective date of  this AD, do the  actions
    specified in paragraphs  (i)(1) and (2)  of this AD.  For airplanes on
    which the  actions specified  in Boeing  Service Bulletin  767-28-0034
    have been done, the actions specified in this paragraph are no  longer
    required for that airplane and the actions specified in paragraph  (k)
    of this AD must be done before further flight.

(1) Revise  the  "Extended Range Operations"  section  of  the  Section  1
    Certificate  Limitations  of  the existing  AFM  by  incorporating the
    information specified in figure 5 to paragraph (i)(1) of this AD. This
    may be done by inserting a copy of this AD into the existing AFM. When
    a statement identical to that in figure 5 to paragraph (i)(1) of  this
    AD has been included in the "Extended Range Operations" section of the
    Section  1 Certificate  Limitations of  the general  revisions of  the
    existing AFM, the general revisions may be inserted into the  existing
    AFM, and the copy of this AD may be removed from the existing AFM.

       FIGURE 5 TO PARAGRAPH (I)(1) – MODEL 767 AFM SECTION 1 REVISION    
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check for  Airplanes  with  a  Single
    Crossfeed Valve (Required by AD 2019-19-10)

    Prior to each extended operations (ETOPS) flight, an operational check
    of the fuel crossfeed valve must be performed. This check must be per-
    formed by the flight crew prior to each ETOPS flight  as  part  of the
    pre-flight procedure  for each specific extended range flight,  or  by
    the maintenance crew no earlier than one hour prior to the flight crew
    boarding the airplane for the purpose of flight.
    ______________________________________________________________________

(2) Revise  the  "Extended Range Operations" section of Section 3.1 Normal
    Procedures of the existing AFM by incorporating the information speci-
    fied in figure 6 to paragraph (i)(2)  of this AD.  This may be done by
    inserting a copy of  this AD into the  existing AFM. When a  statement
    identical to that in figure 6 to paragraph (i)(2) of this AD has  been
    included in  the "Extended  Range Operations"  section of  Section 3.1
    Normal Procedures of  the existing AFM,  the general revisions  may be
    inserted into the existing AFM, and the copy of this AD may be removed
    from the existing AFM.

      FIGURE 6 TO PARAGRAPH (I)(2) – MODEL 767 AFM SECTION 3.1 REVISION   
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check (Required by AD 2019-19-10)

    Unless accomplished by maintenance personnel as part of preparing the
    airplane for the specific ETOPS flight, do the following steps on the
    ground prior to engine start.

    Crossfeed selector.......ON
    Verify that the VALVE light illuminates, then extinguishes

    Crossfeed selector.......OFF
    Verify that the VALVE light illuminates, then extinguishes

    If the VALVE light is inoperative,  it  is  acceptable  to have ground
    personnel verify  by direct observation the opening and closing of the
    crossfeed valve during this procedure.
    ______________________________________________________________________

(j) MEL REVISIONS  FOR MODEL 757 AIRPLANES EQUIPPED  WITH DUAL FUEL CROSS-
    FEED VALVES

    For airplanes identified  in paragraph (c)(2)  of this AD  having line
    numbers 519 and subsequent; and for airplanes identified in  paragraph
    (c)(2) of  this AD  having line  numbers 1  through 518  inclusive, on
    which a second fuel crossfeed  valve has been installed, as  specified
    in  Boeing Service Bulletin 757-28-0029:  Within 120  days  after  the
    effective date of this AD, revise the operator’s existing FAA-approved
    MEL  by  incorporating  the  information  specified  in  figure  7  to
    paragraph  (j) of  this AD  as  a  required operations  procedure when
    dispatching for  ETOPS operation  with an  inoperative fuel  crossfeed
    valve.  Specific alternative  MEL wording  to accomplish  the  actions
    specified in figure 7 to paragraph  (j) of this AD can be  approved by
    the operator’s principal operations inspector (POI).

              FIGURE 7 TO PARAGRAPH (J) – MODEL 757 MEL REVISION          
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check (Required by AD 2019-19-10)

    Unless accomplished by maintenance personnel  as part of preparing the
    airplane for the specific ETOPS flight,  do the following steps on the
    ground prior to engine start.

    Crossfeed selector.......ON
    Verify that the VALVE light illuminates, then extinguishes

    Crossfeed selector.......OFF
    Verify that the VALVE light illuminates, then extinguishes

    If the VALVE light is inoperative,  it  is  acceptable  to have ground
    personnel verify by direct observation the opening  and closing of the
    crossfeed valve during this procedure.
    ______________________________________________________________________

(k) MEL REVISIONS  FOR MODEL 767 AIRPLANES EQUIPPED  WITH DUAL FUEL CROSS-
    FEED VALVES

    For  airplanes  identified  in paragraph (c)(3) of this AD having line
    numbers 431 and subsequent; and for airplanes identified in  paragraph
    (c)(3) of this AD having line numbers 1 through 430 inclusive on which
    a second  fuel crossfeed  valve has  been installed,  as specified  in
    Boeing  Service  Bulletin  767-28-0034:  Within  120  days  after  the
    effective date of this AD, revise the operator’s existing FAA-approved
    MEL  by  incorporating  the  information  specified  in  figure  8  to
    paragraph  (k) of  this AD  as  a  required operations  procedure when
    dispatching for  ETOPS operation  with an  inoperative fuel  crossfeed
    valve.  Specific alternative  MEL wording  to  accomplish  the actions
    specified in figure 8 to paragraph  (k) of this AD can be  approved by
    the operator’s POI.

              FIGURE 8 TO PARAGRAPH (K) – MODEL 767 MEL REVISION          
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check (Required by AD 2019-19-10)

    Unless accomplished  by maintenance personnel as part of preparing the
    airplane for the specific ETOPS flight,  do the following steps on the
    ground prior to engine start.

    Crossfeed selector.......ON
    Verify that the VALVE light illuminates, then extinguishes

    Crossfeed selector.......OFF
    Verify that the VALVE light illuminates, then extinguishes

    If the VALVE light is inoperative,  it is acceptable  to  have  ground
    personnel verify  by direct observation the opening and closing of the
    crossfeed valve during this procedure.
    ______________________________________________________________________

(l) MEL REVISIONS FOR MODEL 777 AIRPLANES

    For airplanes identified  in paragraph (c)(4) of this AD:  Within  120
    days  after  the effective  date  of this  AD,  revise the  operator’s
    existing FAA-approved MEL  by incorporating the  information specified
    in figure  9 to  paragraph (l)  of this  AD as  a required  operations
    procedure when  dispatching for  ETOPS operation  with an  inoperative
    fuel crossfeed valve. Specific  alternative MEL wording to  accomplish
    the actions specified in figure 9  to paragraph (l) of this AD  can be
    approved by the operator’s POI.

              FIGURE 9 TO PARAGRAPH (L) – MODEL 777 MEL REVISION          
    ______________________________________________________________________
    Fuel Crossfeed Valve Operational Check (Required by AD 2019-19-10)

    Before  each  departure,  perform  the  following fuel crossfeed valve
    check:

    1. Position operative crossfeed valve on  and  verify  associated FUEL
       CROSSFEED AFT or FWD advisory message does not display.

    2. Position operative crossfeed valve off and  verify  associated FUEL
       CROSSFEED AFT or FWD advisory message does not display
    ______________________________________________________________________

(m) MEL REVISIONS FOR MODEL 787 AIRPLANES

    For  airplanes  identified in paragraph (c)(5) of this AD:  Within 120
    days  after  the effective  date  of this  AD,  revise the  operator’s
    existing FAA-approved MEL  by incorporating the  information specified
    in figure 10 to paragraph (m) of this AD into the MEL requirements for
    each of the inoperative  items specified in paragraphs  (m)(1) through
    (4) of  this AD.  Specific alternative  MEL wording  to accomplish the
    actions specified  in figure  10 to  paragraph (m)  of this  AD can be
    approved by the operator’s POI.

(1) 28-21-01-01 Pressure Refueling System, Main Tank Inboard Refuel Valve.

(2) 28-22-06 Fuel Balance Switch.

(3) 28-26-01 Defuel/Isolation Valves.

(4) 28-41-01-01 Main Tank Fuel Quantity Indication Systems.

             FIGURE 10 TO PARAGRAPH (M) – MODEL 787 MEL REVISION          
    ______________________________________________________________________
    (Required by AD 2019-19-10)

    Before the first ETOPS departure after the (insert the name of the ap-
    plicable dispatch relief item identified  in paragraphs (m)(1) through
    (m)(4) of AD 2019-19-10) is determined to be inoperative,  perform the
    following maintenance (M) procedure prior to flight.  If the  item re-
    mains inoperative,  this maintenance procedure is not required on sub-
    sequent ETOPS departures  if the crossfeed valve operated  normally on
    the operations (O) pre-flight check.

    MAINTENANCE (M)
    Verify crossfeed valve operates normally.

    1. Gain access to the crossfeed valve in the main gear wheel well.

    2. Set Fuel Control Panel (P5) CROSSFEED switch  to  ON  and  visually
       confirm the valve drive moves  from the closed (C) position  to the
       open (O) position.

    3. Set Fuel Control Panel (P5) CROSSFEED switch  to  OFF  and visually
       confirm the valve drive moves  from the open (O) position to closed
       (C) position.

    Before each ETOPS flight conducted with this item inoperative, perform
    the following operational check as part of the pre-flight check of the
    airplane.  This check may be performed  by  either  the flight crew or
    ground crew.

    OPERATIONS (O)

    1. Prior to each flight, verify crossfeed valve operates normally.

    A. Set Fuel Control Panel (P5) CROSSFEED switch to  ON  and  after  15
       seconds confirm FUEL CROSSFEED advisory message does not display.

    B. Set Fuel Control Panel (P5) CROSSFEED switch to OFF  and  after  15
       seconds confirm FUEL CROSSFEED advisory message does not display.

    2. For fuel balancing, do the FUEL BALANCE SYS Non-Normal Checklist.
    ______________________________________________________________________

(n) AD 88-21-03 R1 AFM LIMITATION REMOVAL

    After the applicable AFM limitations specified  in  paragraphs (g)(1),
    (h)(1),  and  (i)(1) of this AD are incorporated  into  an  airplane’s
    existing  AFM,  operators may remove the AFM limitation required by AD
    88-21-03 R1, for that airplane.

(o) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The  Manager,  Seattle ACO Branch,  FAA,  has the authority to approve
    AMOCs for this AD, if requested  using the procedures found in 14  CFR
    39.19. In  accordance with  14 CFR  39.19, send  your request  to your
    principal  inspector  or  local Flight  Standards District  Office, as
    appropriate. If  sending information  directly to  the manager  of the
    certification  office,  send  it  to  the  attention  of  the   person
    identified in paragraph (p) of this AD. Information may be emailed to:
    9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.

(2) Before using any approved AMOC,  notify your appropriate principal in-
    spector,  or  lacking a principal inspector,  the manager of the local
    flight standards district office/certificate holding district office.

(3) An AMOC that provides an acceptable level of safety  may  be  used for
    any repair, modification, or alteration  required by this AD if  it is
    approved by The Boeing Company Organization Designation  Authorization
    (ODA) that  has been  authorized by  the Manager,  Seattle ACO Branch,
    FAA,  to  make those  findings.  To be  approved,  the repair  method,
    modification  deviation,  or   alteration  deviation  must   meet  the
    certification  basis   of  the   airplane,  and   the  approval   must
    specifically refer to this AD.

(p) RELATED INFORMATION

    For more information about this AD,  contact  Jon Regimbal,  Aerospace
    Engineer, Propulsion Section, FAA Seattle ACO Branch, 2200 South 216th
    St.,  Des Moines, WA 98198;  phone and fax: 206-231-3557;  email: Jon.
    Regimbal@faa.gov.

(q) MATERIAL INCORPORATED BY REFERENCE

    None.

Issued in Des Moines, Washington,  on  October 3, 2019.  Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification Service

FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer, Propul-
sion Section, FAA, Seattle ACO Branch,  2200 South 216th St.,  Des Moines,
WA 98198; phone and fax: 206-231-3557; email: Jon.Regimbal@faa.gov.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-1024; Product Identifier 2017-NM-065-AD; Amendment
39-19746; AD 2019-19-10]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
The Boeing Company Model 737-300, -400, -500, -600, -700, -700C, -800,
-900, and -900ER series airplanes; Model 757 series airplanes; Model
767 series airplanes; Model 777 series airplanes; and Model 787-8 and
787-9 airplanes. This AD was prompted by reports of fuel crossfeed
valves failing to open when activated during flight. This AD requires,
for certain airplanes, revising the existing airplane flight manual
(AFM); and for certain other airplanes, revising the existing minimum
equipment list (MEL) to do an operational check of the fuel crossfeed
valve prior to each extended operations (ETOPS) flight if one fuel
crossfeed valve (or the fuel balancing system on Model 787 airplanes)
is inoperative. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective January 16, 2020.

ADDRESSES:

Examining the AD Docket

You may examine the AD docket on the internet at https://www.regulations.gov
by searching for and locating Docket No. FAA-2017-
1024; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this final rule, the regulatory evaluation, any comments received, and
other information. The address for Docket Operations is U.S. Department
of Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer,
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des
Moines, WA 98198; phone and fax: 206-231-3557; email:
Jon.Regimbal@faa.gov.

SUPPLEMENTARY INFORMATION
:

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all The Boeing Company
Model 737-300, -400, -500, -600, -700, -700C, -800, -900, and -900ER
series airplanes; Model 757 series airplanes; Model 767 series
airplanes; Model 777 series airplanes; and Model 787-8 and 787-9
airplanes. The NPRM published in the Federal Register on December 5,
2017 (82 FR 57383). The NPRM was prompted by reports of fuel crossfeed
valves failing to open when activated during flight. The NPRM proposed
to require, for certain airplanes, revising the existing AFM; and for
certain other airplanes, revising the existing MEL to do an operational
check of the fuel crossfeed valve prior to each ETOPS flight if one
fuel crossfeed valve (or the fuel balancing system on Model 787
airplanes) is inoperative.
The FAA is issuing this AD to prevent an airplane from being
dispatched on an ETOPS flight with a single fuel crossfeed valve (due
to design or due to MEL dispatch of a dual crossfeed valve equipped
airplane with one crossfeed valve inoperative) that cannot be opened or
a fuel balancing system that cannot properly operate when activated.
This condition could cause the fuel in the main tank associated with a
failed engine to be unavailable to the remaining operative engine,
potentially resulting in a forced off-airport landing due to exhaustion
of the remaining usable fuel and consequent loss of all engine thrust.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.

Request To Withdraw the NPRM

United Airlines (UAL) and Delta Air Lines (DAL) asked that the NPRM
be withdrawn until corrective action is proposed with an adequate level
of safety.
UAL stated that the FAA processes leading to issuing the NPRM did
not include certain expected elements (e.g., risk analysis, adequate
cost analysis [which the FAA addresses in the ``Request to Increase
Cost Estimate'' comment], and consideration for airplanes equipped with
aircraft health monitoring (AHM) [which the FAA addresses in the
``Request to Exclude Airplanes with AHM'' comment]). UAL added that it
is not aware of an FAA risk analysis of a simultaneous engine failure and a
crossfeed valve failure during an ETOPS flight in a critical fuel location.
UAL conducted a risk analysis and provided the following comments
and questions:
The NPRM specified that the FAA had received reports of
fuel crossfeed valves failing to open when activated during flight, but
provided no data.
The NPRM provided no statistical analysis of industry
engine failure rates, or of crossfeed valve failure rates. What is the
probability that an engine will fail and a crossfeed valve will fail on
the same ETOPS flight in a fuel-critical location?
ETOPS-qualified aircraft engine failure rates are
extremely low. UAL engine failure rates vary from 0.005 to 0.000, well
below the 0.030 required for ETOPS certification.
Crossfeed valve failure rates are extremely low (roughly 1
per 100,000 departures), and Boeing had indicated that it did not
regard the failure of crossfeed valves as a potential reliability
issue.
DAL stated that a Boeing risk analysis showed that an engine
shutdown with the inability to transfer fuel is improbable (the FAA
infers that the commenter meant ``extremely improbable'' as used in FAA
risk analysis policy) and that Boeing does not consider this to be a
safety issue. DAL added that cycling the fuel crossfeed valve prior to
further flight, or at any time, does not ensure that the valve will
work as intended at a later point in flight. DAL concluded that the
proposed AD does not provide corrective action that will improve the
safety of the airplane.
The FAA does not agree to withdraw the NPRM. The FAA determined
that the unsafe condition of fuel crossfeed valves failing to open or
fuel balancing systems failing to operate when activated during flight
must be addressed. For transport airplanes, this determination is based
on several criteria, and the failure to meet one or more of the
criteria could lead the FAA to determine that corrective action is
warranted.
For each identified potential safety issue on a transport airplane,
the FAA examines the risk on the worst reasonably anticipated flights
(flights actually predicted to occur) to ensure that each flight
provides an acceptable level of safety [identified as ``individual
flight risk'' in FAA risk analysis policy]. That acceptable level of
safety consists of three basic expectations:
That each flight begins in a fail-safe state (including
consideration of latent failure conditions and allowed dispatch states
under the MEL), meaning that a foreseeable single failure on any
anticipated flight should not have a significant likelihood of causing
a catastrophic event.
That each flight does not have a numerical risk of a
catastrophic event due to the issue being examined that is excessively
(an order of magnitude or more) greater than the risk of a catastrophic
event on an average transport airplane.
That safety features that were prescriptively required due
to lessons learned from past incidents and accidents are not
excessively reduced in their effectiveness or availability.
Failure to meet any of these three criteria can lead to a
determination that an unsafe condition exists and AD action is
necessary, because the level of safety on the affected flights does not
meet the FAA's thresholds for an acceptable level of safety on
individual flights.
For each identified potential safety issue, the FAA also assesses
the total cumulative risk of an event occurring at any time in the
remaining life of the fleet of affected airplanes (identified as
``total fleet risk'' in FAA risk analysis policy). The FAA may
determine that corrective action is needed to limit total fleet risk
even when the assessed individual flight risk does not violate any of
the three individual flight risk criteria discussed above. Total fleet
risk is typically assessed by multiplying the average probabilities of
each of the failures or other factors that contribute to the occurrence
of an event, the total number of airplanes affected, the average
utilization of those airplanes, and the average remaining life for
those airplanes. The FAA also considers the number of occupants of an
aircraft in assessing fleet risk, and applies total fleet risk
guideline thresholds expressed in terms of both aircraft accidents and
number of fatalities.
Either excessive individual flight risk or excessive total fleet
risk, or both, can lead the FAA to determine that an unsafe condition
exists that requires corrective action. The FAA does not use or accept
calculations of acceptable total fleet risk, or acceptable average per-
flight-hour risk, as a justification for taking no action on issues
where an excessive individual flight risk is determined to exist on
flights that are anticipated to occur.
For this AD, the FAA identified that flights of airplanes with a
single operative crossfeed valve (due to design or due to MEL dispatch
of a dual crossfeed valve equipped airplane with one crossfeed valve
inoperative) are expected to occur with a pre-existing undetected
failure of that single crossfeed valve (or of the fuel balancing system
on Boeing Model 787 airplanes). On such a flight, if an engine shutdown
occurs during the fuel-critical ETOPS portion of the flight, it can
lead to fuel exhaustion and a forced off-airport landing. That fuel-
critical portion of the flight can be of significant duration. For
example, according to Boeing, the fuel-critical exposure window (during
which an engine failure without crossfeed capability would lead to fuel
exhaustion prior to reaching a suitable airport under the current 14
CFR part 121 fuel reserve requirements) ranges from approximately 1.8
to 2.3 hours in length for flights between the West Coast of the U.S.
and Hawaii. For ETOPS missions using greater-than-180-minute ETOPS
capability, the exposure can be significantly greater.
While the average probability per flight hour of a failure of the
crossfeed valve and an engine failure in cruise on the same flight has
been shown by Boeing to be extremely improbable (on the order of one
event per billion flight hours), the actual risk is not evenly spread
among flights at the average level. Instead, most of that risk is
currently concentrated in the flights of airplanes operating with a
single crossfeed valve due to design configuration or MEL dispatch
relief, and on which that single crossfeed valve is inoperative due to
a latent failure. On such flights, the estimated average probability of
an engine failure during the cruise phase of flight is in the range of
one event per 100,000 to 1 million flight hours (based on current
industry in-flight engine shutdown data), depending on the engine/
airplane combination. In addition, engine shutdowns can be caused by
many different single failures of engine or airplane components, which
means those flights that begin with an already inoperative crossfeed
valve are not fail-safe for an engine failure as required by the
airworthiness regulations and expected by the public.
Based on the crossfeed valve actuator failure rates supplied by the
Boeing and the current AFM requirements to check the operation of the
crossfeed valves in the last hour of cruise on ETOPS flights, the FAA
estimates that well over 100 flights with inoperative crossfeed valves
will occur in the remaining life of the affected fleet. Such flights do
not provide the level of safety that is intended for ETOPS operations.
Checking the operation of the crossfeed valve immediately prior to each
ETOPS flight will ensure that each flight begins with a crossfeed valve
that was recently verified to operate, and will minimize the likelihood of a
crossfeed valve failing if engine crossfeed is required. The FAA considers a
check of the crossfeed valve operation prior to each ETOPS flight to be
a significant improvement in safety for the flights on which the risk
is actually concentrated, thereby minimizing the chance that an engine
failure on one of those flights will lead to a catastrophic fuel
exhaustion event. For the reasons specified previously, the FAA is
issuing this final rule to address the identified unsafe condition.

Request To Revise Airplanes Affected by Certain Requirements

American Airlines generally supported the NPRM, but asked that the
airplanes affected by paragraphs (h) and (j) of the proposed AD be
corrected. American Airlines stated that paragraphs (h) and (j) of the
proposed AD specify airplanes having line numbers 1 through 616
inclusive and 618; however, the effectivity specified in Boeing Service
Bulletin 757-28-0029 for the corresponding actions is line numbers 1
through 518 inclusive. American Airlines added that airplanes having
line numbers above 518 had the actions specified in the referenced
service information incorporated in production.
The FAA agrees with the commenter's request for the reason
provided. Paragraphs (h) and (j) of this AD have been changed
accordingly.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing (APB) stated that the installation of
winglets per Supplemental Type Certificate (STC) ST01219SE, ST00830SE,
ST01518SE, or ST01920SE does not affect the accomplishment of the
manufacturer's service instructions.
The FAA agrees that STC ST01219SE, ST00830SE, ST01518SE, and
ST01920SE do not affect the accomplishment of the manufacturer's
service instructions. Therefore, the installation of STC ST01219SE,
ST00830SE, ST01518SE, or ST01920SE does not affect the ability to
accomplish the actions required by this AD. The AD has not been changed
in this regard.

Request To Increase Cost Estimate

UAL stated that the FAA did not include adequate cost analysis and
stated the FAA should consider the negative effects of daily activation
of the crossfeed valve on mean time between failure (MTBF) rates, or
the associated cost of increased valve replacement rates.
The FAA infers that UAL is asking that the cost estimate in the
``Costs of Compliance'' section of this final rule be increased to
account for a decreased MTBF for the crossfeed valve or actuator. The
FAA does not agree to increase the estimated costs. The FAA normally
addresses only the direct cost of a required action, and the agency has
not received any data from the manufacturer or operators indicating
that actuating the crossfeed valve prior to each ETOPS flight will
significantly increase the crossfeed valve failure and replacement
rate.
Relative to the effects of daily activation of the crossfeed valve,
a significant decrease in MTBF will likely not result from the actions
in this AD, for the following reasons:
The various fuel system valves and valve actuators are all
of similar designs, and some of those valves are cycled once or more
per flight. They are designed to operate for many thousands of cycles
without failure.
For airplanes equipped with a single crossfeed valve, the
existing AFM requires operators to perform an operational check of the
crossfeed valve in the last hour of cruise of every ETOPS flight. This
AD requires the same check to be performed prior to each ETOPS flight,
and provides relief from the existing requirement for a valve
operational check in the last hour of cruise.
For airplanes with dual crossfeed valves or a fuel
balancing system (for Boeing Model 787 airplanes), this AD requires a
crossfeed valve operational check only when the airplane is operated
under the MEL with a crossfeed valve or fuel balance system
inoperative.
Therefore, this AD will not require a significantly increased total
number of valve operational checks to be performed; the AD just changes
when the check is performed. In light of these factors, this AD has not
been changed in this regard.

Request To Exclude Airplanes With AHM

UAL asked to revise the applicability of the proposed AD to exclude
airplanes that have an AHM system capable of reporting an impending
crossfeed valve failure before an actual service failure occurs. UAL
did not provide a reason for its request, but the FAA infers that the
commenter considered that a system that can detect an impending
crossfeed valve failure before an actual crossfeed valve failure
occurs, leading to a precautionary crossfeed valve or actuator
replacement, would provide an acceptable way to address the unsafe
condition.
The FAA does not agree with the commenter's request. The FAA is not
aware of any of the affected airplanes having the capability to detect
and annunciate an impending crossfeed valve failure. UAL did not
identify a specific airplane or installed system feature that has that
capability. Operators may apply for an alternative method of compliance
(AMOC) in accordance with paragraph (o) of this AD, provided they can
show that such a system is available for installation on an airplane
and adequately addresses the unsafe condition. The AD has not been
changed in this regard.

Request To Allow Alternative AFM Approval

Southwest Airlines (SWA) contended that use of the term
``identical'' in paragraph (g)(2) of the proposed AD would be
unnecessarily restrictive and could prevent operators from using
previously accepted formatting standards and layout. SWA therefore
asked that paragraph (g)(2) of the proposed AD be revised to add the
following statement: ``Alternative statements that meet the intent of
the following requirements may be used if approved by an appropriate
FAA POI.'' SWA added that a similar principal operations inspector
(POI) allowance was provided in AD 2011-18-03, Amendment 39-16785 (76
FR 53317, August 26, 2011).
The FAA does not agree with the commenter's request. The intent of
this AD is for the text of the general AFM revision limitations and
procedures to be identical to that required by the AD; however,
formatting and layout can be changed without an approved AMOC as long
as those changes do not change the text of the statements. Operators
may apply for an AMOC in accordance with paragraph (o) of this AD for
any changes to the text required by the AD. The AD has not been changed
in this regard.

Request To Include Certain Provisions Required by Original Type Design

Boeing asked that paragraph (n) of the proposed AD be changed to
eliminate certain existing requirements for airplanes on which a last-
hour-of-ETOPS-flight crossfeed valve operational check is in the AFM as
part of the type certificate approval. Boeing stated that after
publication of AD 88-21-03 R1, Amendment 39-6077 (53 FR 46605, November
18, 1988) (``AD 88-21-03 R1''), new airplane models with a single
crossfeed valve that were not affected by the requirements in AD 88-21-
03 R1 had a similar requirement in the AFM as part of the airplane type certificate.
The FAA does not agree with the commenter's request. The FAA
approval of the AFM change proposed by the commenter would be
considered an approval of a voluntary change to a type certificate.
Such changes are required to be approved under the process defined in
14 CFR part 21 and are not accomplished through an AD. Once the
operational check prior to each ETOPS flight is incorporated into the
existing AFM or MEL as required by this AD, the check required in the
last hour of cruise by the existing AFM could be eliminated through a
type certificate design change approval. If Boeing or an operator wants
to obtain approval of a revised AFM without the limitation requiring
the last-hour-of-ETOPS-flight crossfeed valve operational check, the
request can be submitted for FAA approval using the normal process for
obtaining approval of a revised AFM. Therefore, the AD has not been
changed in this regard.

Request To Revise Headings for Certain Figures

Boeing asked that the FAA expand the headings for the AFM text in
figure 3 to paragraph (h)(1) of the proposed AD and figure 5 to
paragraph (i)(1) of the proposed AD by adding ``The following is
applicable prior to incorporation of Boeing Service Bulletin 757-28-
0029 or production equivalent,'' and ``The following is applicable
prior to incorporation of Boeing Service Bulletin 757-28-0034 or
production equivalent,'' respectively. Boeing stated that the
referenced service information and production equivalent are closing
actions for the applicable AD.
The FAA partially agrees with the commenter's request. The FAA
agrees to change these headings, because an operator could have a mixed
fleet of single- and dual-valve airplane configurations operating under
a single AFM version, which should have limitation language that is
applicable only to airplanes with a single crossfeed valve. However,
the FAA does not agree with making the specific change by referencing
only service bulletins or production equivalent configurations, because
while limitations with similar language have been approved in the past,
the flight crew does not have readily available information on the
service bulletins or production changes that are installed. However,
the crew can readily identify whether the airplane has one or two
crossfeed valves simply by looking at the overhead fuel control panel,
where either one or two crossfeed valve switches are installed.
Therefore, the referenced headings in this AD have been changed to
refer to the crossfeed valve configuration rather than the service
bulletin number.

Request To Eliminate the Operational Requirement in the MMEL

Boeing asked that the proposed operational requirement for
airplanes with dual crossfeed valves operating on the master minimum
equipment list (MMEL) be eliminated. Boeing stated that after
publication of AD 88-21-03, which required operational checks of the
crossfeed valves in the last hour of each ETOPS flight for airplanes
equipped with a single crossfeed valve, the FAA approved the
installation of a second crossfeed valve as an AMOC for that AD,
without requiring any crossfeed valve checks if the airplane is
operated with a crossfeed valve inoperative under the MEL. Boeing added
that it is not necessary to now mandate an operational check for an
airplane operating with a crossfeed valve inoperative under the MEL.
Boeing stated that the fundamental criterion for MMEL relief is
that an acceptable level of safety must be maintained considering the
next critical single failure event in flight. Boeing also stated that
operation with a crossfeed valve or transfer system inoperative under
the current MMEL requires verification that the remaining crossfeed
valve is operative, and that in-flight failure of the remaining
crossfeed valve during a subsequent flight would not itself create an
unsafe condition. Boeing added that issuing an AD to require
operational checks for operation under the MMEL is therefore redundant.
Boeing cited the preamble language required by the FAA in MMEL
Policy Letter 34, Revision 4, dated August 15, 1997:

Experience has shown that with the various levels of redundancy
designed into aircraft, operation of every system or installed
component may not be necessary when the remaining operative
equipment can provide an acceptable level of safety.

Boeing stated that the addition of a redundant crossfeed valve
provides a fault-tolerant configuration, which experience has shown
provides an acceptable level of safety. Boeing concluded that unless
credit is given for the redundant crossfeed valve without a requirement
for an operational check, the redundant valve provides no added safety
benefit and therefore could be eliminated.
The FAA does not agree with the commenter's request. When the FAA
determines that an existing MMEL relief provision does not provide an
acceptable level of safety, the FAA may either eliminate or modify that
relief through AD action. In this case, the FAA determined that an
operational check of the crossfeed valve, prior to each ETOPS flight
that takes place with a single crossfeed valve, is necessary to prevent
dispatch of an ETOPS flight with no ability to access all of the
remaining fuel in the event of an engine failure. The FAA has further
determined that flights without the ability to access all of the
remaining fuel would not provide an acceptable level of safety, because
a single engine failure during the critical portion of the cruise phase
could result in a forced offairport landing due to inadequate usable
fuel available to the operative engine. This check is necessary when an
airplane equipped with a dual crossfeed valve is dispatched under the
MMEL with one crossfeed valve inoperative or with the fuel balancing
system inoperative, for the same reason that the crossfeed valve
operational check is required prior to each ETOPS flight on an airplane
with a single crossfeed valve.
The citation from MMEL Policy Letter 34 is from the standardized
language required by that policy letter to be included in the preamble
of an MMEL. It is simply an introductory statement indicating that
redundant systems may allow for dispatch with certain equipment
inoperative in some cases. It is not intended to restrict the
conditions or limitations that the FAA may place on a particular MMEL
relief provision. The failure of a crossfeed valve in a manner that
will prevent it from actuating is typically detected only through
subsequent attempted actuation of the crossfeed valve for fuel
balancing, or for crossfeed in the event of an engine failure.
Therefore, the failure of the crossfeed valve is likely to remain
undiscovered from the time of the failure until the next attempt at
actuation. This latency period may occur during several flights in some
operational situations, such as movement of an individual airplane to
an ETOPS route when that airplane has previously been operated on non-
ETOPS routes. That operational situation and the associated latency
period increases the likelihood that the crossfeed valve on that
airplane will fail when the next attempt is made to actuate the
crossfeed valve. An operational check of the crossfeed valve
immediately prior to each ETOPS flight (the flights where the ability
to open the crossfeed valve may be critical) is a practical measure to
minimize the likelihood that the crossfeed valve will fail to open if
needed, and to ensure that the flight is started with an operative crossfeed
valve.
The addition of a second crossfeed valve provides redundancy that
the FAA determined in the past was an acceptable substitute for a
preflight operational check, and that also could allow for dispatch
with one crossfeed valve inoperative. However, since that time the FAA
has determined that when an airplane is operated with a crossfeed valve
(or a fuel balancing system) under the MEL, it should be operated with
the same crossfeed valve operational check requirement as an airplane
with a single crossfeed valve configuration, for the same reason that
the preflight operational check is required for an airplane with a
single crossfeed valve configuration. Therefore, the AD has not been
changed in this regard.

Request To Correct Errors in Figure 10

Boeing, UAL, All Nippon Airways (ANA), and Captain David Stewart
(Captain Stewart) asked that the language specified in figure 10 to
paragraph (m) of the proposed AD be corrected to reflect that the
allowed MMEL dispatch relief in that figure is for the fuel balance
system instead of the crossfeed valve. UAL listed four specific MMEL
provisions (specified in paragraphs (m)(1) through (4) of this AD) that
are for various inoperative components or systems that cause the fuel
balance system to be inoperative. Boeing and ANA stated that the figure
should be revised to reflect that if the crossfeed valve fails to open,
the FUEL CROSSFEED advisory message will not be displayed until 15
seconds after crossfeed is selected ON. Captain Stewart stated that the
language in figure 10 to paragraph (m) of the proposed AD is erroneous
and should have stated ``Before the next ETOPS departure after the Fuel
Balance Switch is determined to be inoperative . . . .''
The FAA agrees with the commenters' requests for the reasons
provided. Figure 10 to paragraph (m) of this AD has been revised to
correct the errors noted by the commenters.

Request To Revise the MMEL Operational Check Requirements

United Airlines MEL Engineering asked that the MMEL operational
check requirements in figure 4 to paragraph (h)(2) of the proposed AD,
figure 6 to paragraph (i)(2) of the proposed AD, figure 7 to paragraph
(j) of the proposed AD, and figure 8 to paragraph (k) of the proposed
AD be revised to allow the use of either the ``VALVE'' light that is
integral to the crossfeed valve switch, or the associated engine
indication and crew alerting system (EICAS) message for the preflight
operational check. UAL stated that if the ``VALVE'' light is
inoperative, it would be unable to perform the check. UAL noted that
MMEL relief is provided for the crossfeed valve lights.
The FAA does not agree with the commenter's request to perform the
check using the ``FWD/AFT FUEL CROSSFEED'' EICAS message because there
are certain crossfeed valve actuator failure modes that can cause the
crossfeed valve to remain closed without the ``FWD/AFT FUEL CROSSFEED''
EICAS message being displayed. Short of directly observing the valve
actuator, monitoring the VALVE light to verify that the crossfeed valve
actually transitioned from closed to open is the only way to verify
from the flight deck that the crossfeed valve transitioned to the open
position. While MMEL relief is provided for the VALVE light, that
relief is subject to the provision that the crossfeed valve is verified
to operate correctly.
The FAA does agree to allow an alternative procedure that is
effective if the ``VALVE'' light is inoperative, because it is possible
to perform an operational check of the crossfeed valve by directly
observing the movement of the actuator if the ``VALVE'' light is
inoperative. The FAA has revised the referenced figures in this AD
accordingly.

Request To Revise Crossfeed Valve Operational Check

The Air Line Pilots Association, International (ALPA), Allied
Pilots Association (APA), and Captain Stewart asked for revisions to
the operational checks specified in the proposed AD. Captain Stewart
asked that certain crossfeed valve actions in the proposed AD be
changed to require one of the following: (1) Performing the crossfeed
valve operational check in flight, prior to entering the ETOPS segment
of the flight, and diverting the airplane to a suitable airport if the
check fails, or (2) opening the crossfeed valve prior to entry into the
ETOPS segment, leaving the crossfeed valve open throughout the ETOPS
segment, and diverting the airplane to a suitable airport if the valve
fails to open. Captain Stewart pointed out that operation with the
crossfeed valve open for the duration of the ETOPS portion of the
flight was proven effective at a major airline.
ALPA, while supporting the inclusion of an operational check prior
to dispatch of ETOPS flights, stated that since the action in the
proposed AD is not directed at a specific crossfeed valve failure mode,
and is instead intended to identify and minimize the exposure to any
crossfeed valve failure mode, it is important to check the crossfeed
valve in its normal operating environment during flight. ALPA therefore
requested that the proposed AD be revised to include an AFM requirement
for airplanes with only one crossfeed valve, and a MEL requirement for
airplanes with two crossfeed valves, for an operational check of the
crossfeed valve during cruise, prior to the entering ETOPS airspace.
APA had no objection to the steps for checking the crossfeed valve
operation, using the procedure recommended by the original equipment
manufacturer (OEM). APA recommended checking the crossfeed valve
immediately prior to the ETOPS segment of the flight where its
operation has the potential to be critical.
The FAA does not agree with the commenters' requests. Although the
agency agrees that operationally checking the crossfeed valve
immediately prior to entering the critical ETOPS portion of each ETOPS
flight would provide a greater reduction in the risk that a crossfeed
valve will fail to open in the fuel-critical phase of flight should an
engine failure occur, it would also significantly increase the costs
associated with each discovered failure of a crossfeed valve. The cost
of an air turn-back or diversion is significantly higher than the cost
of a delay for maintenance, and is likely to be greater than the cost
of a flight cancellation. The FAA considered the additional costs that
would be incurred by operators from an air turn-back or diversion each
time a crossfeed valve fails its check, and also considered the
additional reduction in exposure to latent crossfeed valve failures
that develop between the time of a preflight check and the time of an
ETOPS entry check. As a result of these considerations, the FAA
determined that the incremental reduction in exposure to the
development of a latent crossfeed valve failure due to checking the
crossfeed valve in-flight prior to entry into the critical ETOPS
portion of the flight, when the low probability of an engine failure is
also considered, did not justify imposing those significant additional
operational costs and service disruptions on affected operators.
Before the NPRM was published, the FAA discussed with Boeing the
value of conducting the crossfeed valve operational check during flight
under cold soak conditions (which are part of the normal operating
environment), versus performing the check on the ground. As a result of
some of the comments on the NPRM, the agency discussed this issue again
with Boeing, and placed a record of that discussion
in the public rulemaking docket. Boeing stated that the valve actuator
failure modes identified by other commenters that result in actuator
failures only in cold soak conditions have been corrected in newer
designs. Boeing further stated that the previous valve actuator
configurations that had those issues are no longer in service. Boeing
added that it had no reason to believe that a check of the current in-
service crossfeed valves under cold, in-flight conditions would detect
failures that would not be detected on the ground.
In addition, the FAA does not agree with the request to require
operation with the crossfeed valve open throughout the ETOPS segment of
flight. While operation in that configuration would prevent the need to
open the crossfeed valve in the event of an engine failure, there are
other failure scenarios (such as a large fuel leak or contamination of
one main tank) where operating with the crossfeed valve open
compromises the intended isolation and independence of the fuel system
for each engine. Also, differences in fuel pump performance could cause
the need for repeated switching off and on of fuel pumps to maintain
balanced main tanks. The FAA considers this undesirable because a
flight crew error could put one or both engines on suction feed,
potentially causing engine flameout. It would also add start/stop
cycles on the fuel pumps, which could cause additional pump failures.
Such a procedure is not recommended or approved by either Boeing or the
FAA. Finally, that procedure violates the required fuel usage
procedures in the limitations section of the FAA-approved AFMs for all
of the affected airplane models, which require the airplane to be
operated with the crossfeed valve closed except when it is specifically
required to be open for crossfeeding to maintain balanced main tanks or
for a low fuel condition. Therefore, that procedure would also violate
14 CFR 91.9, which requires operators to operate aircraft in accordance
with their applicable AFM limitations, unless a revised AFM was
approved. In light of all these factors, the AD has not been changed in
this regard.

Request To Change MMEL-Related Requirements

Captain Stewart recommended that the proposed AD be revised to
require an MMEL revision with clearly written provisions that identify
the appropriate verification to confirm that no latent faults exist.
Captain Stewart added that there is no benefit in mandating specific
(M) & (O) procedures in the proposed AD, because it would cause an
unnecessary administrative burden. Captain Stewart concluded that MELs
published without the adequate (M) & (O) procedures indicates a failure
of the MEL review/approval process at the flight standards district
office (FSDO) or certificate management office (CMO) level.
The FAA infers that the commenter is requesting that the MEL
entries for operation with an inoperative crossfeed valve or fuel
balancing system (for Model 787 airplanes) state the requirement for
and objectives of the MEL maintenance and operational requirements,
rather than mandating specific maintenance or operational procedures.
The FAA does not agree with the commenter's request. In this case,
there are various ways that the operational or maintenance check can be
done, some of which would not detect all of the possible crossfeed
valve failure modes. Therefore, the FAA has determined that the agency
should maintain control over the operational and maintenance check
procedures used. Operators may, however, apply for an AMOC in
accordance with paragraph (o) of this AD, provided they can show that
their proposed alternative operational or maintenance procedures
adequately address the unsafe condition. The AD has not been changed in
this regard.

Request To Exempt Certain Airplanes

FedEx asked that the proposed AD be revised to exclude airplanes
that are not used for ETOPS operations from the proposed requirement to
revise the existing AFM and MEL. Specifically, FedEx requested that
paragraphs (h), (i), (j), and (k) of the proposed AD be revised to add
``Airplanes that are not used for ETOPS operations are exempt from the
requirements of this paragraph.'' FedEx stated that the proposed AD
does not allow for exemption of affected fleets that are not certified
or utilized for ETOPS operations. FedEx reported that its fleets
include the types of airplanes affected by the proposed AD, but that
only its Model 777F airplanes are certified for ETOPS operations.
The FAA does not agree with the commenter's request. The addition
of the language proposed by the commenter is not sufficient to ensure
that the existing AFM and MEL will be updated as required by this AD if
there is an operational change in the future. However, operators may
apply for an AMOC in accordance with paragraph (o) of this AD, provided
they submit a proposal that (1) describes how the operator will ensure
that future introduction of ETOPS operations includes the required AFM
and MEL changes and (2) is supported by its FAA POI. The AD has not
been changed in this regard.

Request To Clarify Instructions for Operational Check

FedEx and Japan Airlines (JAL) asked that the language in figure 8
to paragraph (k) of the proposed AD be revised to include instructions
for a fuel crossfeed valve operational check including ``steps on the
ground prior to engine start.'' The commenters requested that ``prior
to engine start'' be changed to ``prior to each flight.'' FedEx stated
that this language should be clarified given that the intent of the
proposed AD is to prevent fuel in the main tank associated with the
failed engine from being unavailable to the remaining operative engine,
potentially resulting in a forced off-airport landing. JAL stated that
the time for performing the operational check in the proposed AD is
more restrictive than that in the MMEL. JAL added that since both are
the same action, that compliance time should be the same.
The FAA acknowledges the commenters' concerns regarding potential
misunderstanding of when to perform the operational check, and agree
that clarification is necessary. The FAA infers that FedEx found that
figure 8 to paragraph (k) of this AD was not sufficiently clear that
the operational check is intended to be performed prior to each flight.
The FAA presumes that FedEx's concern is that an operator might perform
the operational check only once prior to the first engine start after
placing the other inoperative crossfeed valve on MEL relief, but not
prior to subsequent flights on the MEL. The intent of the procedure is
that an operational check of the crossfeed valve be performed, by
maintenance personnel or flightcrew, immediately prior to each ETOPS
flight, as was stated in the ``Proposed AD Requirements'' section of
the NPRM.
The FAA disagrees with using the specific language proposed by
FedEx because its language would not alleviate the confusion about the
intent of the requirement, and might be interpreted as allowing the
check to be performed at any time prior to flight, as opposed to
immediately prior to each flight. Although the comment from FedEx
requested a change to figure 8 to paragraph (k) of this AD, which
provides the required MEL revision for the Model 767, the FAA is
satisfied that the MEL language in figure 7 to paragraph (j) of this
AD, figure 8 to paragraph (k) of this AD, figure 9 to paragraph (l) of
this AD, and figure 10 to paragraph (m) of this AD is clear with respect to
the intended timing of performing the crossfeed valve operational check.
The general intent of operational procedures in the existing MEL is
that they are associated with each flight conducted with the
inoperative equipment. However, the comments provided caused the agency
to reconsider whether the corresponding language in the AFM revisions
required for airplanes equipped with single crossfeed valves are
sufficiently clear regarding the intended timing for the check. In
light of this, figure 1 to paragraph (g)(1) of this AD, figure 3 to
paragraph (h)(1) of this AD, and figure 5 to paragraph (i)(1) of this
AD of this AD have been revised to clarify the AFM limitations on
airplanes equipped with a single crossfeed valve. However, the language
in other figures, including figure 8 to paragraph (k) of this AD, have
not been changed.

Request To Change Time for Performing Operational Check

DAL asked that the time for performing the operational check be
changed to the last hour of the cruise flight, instead of prior to each
ETOPS flight. DAL stated that solder joint cracks at the connectors and
electronic assembly could cause intermittent or hard fault failure of
the motor-operated crossfeed valves (MOVs) that is difficult to detect
during the ground test prior to each ETOPS flight. DAL added that a
cold soak test at the end of the cruise flight will better detect
intermittent MOV failures than a test performed on the ground.
The FAA does not agree with the commenter's request. At the FAA's
request, Boeing examined the commenter's statements, and Boeing
provided comments. A record of the phone conversation in which Boeing
provided its comments was placed in the public rulemaking docket for
this AD. Boeing stated that the valve actuator failure modes described
by DAL that tended to occur in cold conditions were successfully
addressed by design improvements, and that the valve actuator
configurations that were susceptible to failures that could only be
detected in cold conditions have been replaced on operational aircraft
and are no longer in service. Boeing added that its more recent failure
data shows that the timing of failures is random, and that the ability
to detect a failed crossfeed valve is no longer significantly impacted
by environmental conditions during the operational check.
As previously discussed, the FAA has determined that the greatest
practical reduction in risk during operation with a single operational
crossfeed valve would be achieved by requiring the operational check as
close as possible to the beginning of the fuel-critical ETOPS portion
of the flight. However, as noted, the impact of requiring the
operational check in flight, just prior to entry into the ETOPS portion
of the flight, would cause a significant number of air turn-backs and
diversions at significant cost, so the FAA, with agreement from Boeing,
proposed the check requirement for immediately prior to each ETOPS
flight. Therefore, this AD has not been changed in this regard.

Request To Reduce Compliance Time

ALPA asked that the compliance time be reduced from 120 to 90 days.
ALPA stated that the proposed AD would not require extensive, one-time
maintenance actions on affected airplanes, but only revision of
existing AFM and MEL actions, thus the commenter recommended a shorter
compliance time.
The FAA does not agree with the commenter's request. In conjunction
with Boeing, the FAA has determined that the compliance time for each
airplane model will accommodate the time necessary to accomplish the
actions required by this AD and maintain an adequate level of safety.
In addition, the suggested compliance time change would alter the
requirements of this AD, so additional rulemaking would be required,
ultimately delaying issuance of the AD. The FAA finds that delaying
this action further is inappropriate in light of the identified unsafe
condition. However, if additional data are presented that would justify
a shorter compliance time, the FAA may consider further rulemaking on
this issue. The AD has not been changed in this regard.

Request To Add Airplanes to Applicability

American Airlines asked that Model 737-7, -8, and -9 (MAX)
airplanes be added to the applicability of the proposed AD. American
Airlines stated that the design on these airplanes is similar to that
of the Model 737 Classic and Next Gen airplanes.
The FAA does not agree with the request. Although the commenter is
correct about the similar design, this unsafe condition was identified
at the time of certification of the 737 MAX airplanes as a planned
airworthiness directive against the existing Model 737 airplanes.
Therefore, Boeing included the requirement for the operational check of
the crossfeed valve required by this AD in the FAA-approved AFM for the
737 MAX airplanes. The AD has not been changed in this regard.

Engineering Oversight

Captain Stewart and APA stated that it is an engineering oversight
that new production ETOPS airplanes are being certificated with only
one fuel crossfeed valve installed.
The FAA acknowledges the commenter's concern about the risk
associated with two-engine ETOPS airplanes that depend on a single
active component to allow the remaining engine to access all of the
remaining fuel on board after an engine failure. However, the allowance
for such designs was not an engineering oversight, but a result of how
the initial 120-minute ETOPS type-design standards were developed with
existing airplanes in mind, of the later 180-minute ETOPS type-design
standards being developed based on the 120-minute standards, and of
conscious decision making by Boeing and the FAA associated with AD 88-
21-03 R1 (which applies to certain Airbus Model A300 and A310-200
series airplanes, and Boeing Model 737-200, 737-300, 757-200, 767-200,
and 767-300 series airplanes) and certification of the Model 737-700
airplane. Discussion of the potential need for improvements to
airworthiness standards is outside the scope of the actions required by
this AD. Therefore, the AD has not been changed in this regard.

Report of Incident

Commenter Amirul Ismail provided what appears to be a pilot report
of an instance where an operational check of the crossfeed valve on a
Model 737-800 airplane resulted in the VALVE light failing to
extinguish. The incident appears to be an indication-related fault
rather than a valve actuator failure. No change to the final rule has
been made.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this final rule with the changes described previously
and minor editorial changes. The FAA has determined that these minor
changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
The FAA also determined that these changes will not increase the
economic burden on any operator or increase the scope of this final
rule.

Costs of Compliance

The FAA estimates that this AD affects 3,252 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

Action
Labor cost
Parts cost
Cost per product
Cost on U.S. operators
AFM Revision (2,127 airplanes) 1 work-hour x $85 per hour = $85
$0
$85
$180,795
MEL Revision (1,125 airplanes) 1 work-hour x $85 per hour = $85
0
85
95,625

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, part A, subpart III, Section 44701: ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to transport category airplanes and
associated appliances to the Director of the System Oversight Division.

Regulatory Findings

This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39


Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):