DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-0103; Product Identifier 2019-NM-149-AD]
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to supersede Airworthiness Directive
2012-21-08, which applies to certain The Boeing Company Model 737-600,
-700, -700C, -800, and -900 series airplanes. AD 2012-21-08 requires
inspecting for part numbers of the operational program software (OPS)
of the flight control computers (FCCs) and installing and testing an
updated version of the FCC OPS. Since the FAA issued AD 2012-21-08, the
FAA has determined that there is a new unsafe condition which must be
addressed by an updated version of the FCC OPS. This proposed AD would
retain the requirement to inspect for part numbers of the OPS of the
FCCs, and add a new requirement to update the version of the FCC OPS if
necessary. This proposed AD would also expand the applicability to
include The Boeing Company Model 737-900ER series airplanes. The FAA is
proposing this AD to address the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by April
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow
instructions for submitting comments.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For service information identified in this NPRM, contact Boeing
Commercial Airplanes, Attention: Contractual & Data Services (C&DS),
2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600;
telephone 562-797-1717; internet https://www.myboeingfleet.com. You may
view this service information at the FAA, Transport Standards Branch,
2200 South 216th St., Des Moines, WA. For information on the
availability of this material at the FAA, call 206-231-3195. It is also
available on the internet at https://www.regulations.gov by searching
for and locating Docket No. FAA-2020-0103.
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-2020-0103;
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 NPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations is listed above.
Comments will be available in the AD docket shortly after receipt.
FOR FURTHER INFORMATION CONTACT: David Sumner, Aerospace Engineer,
Systems and Equipment Section, FAA, Seattle ACO Branch, 2200 South
216th St., Des Moines, WA 98198; phone and fax: 206-231-3538; email:
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2020-0103;
Product Identifier 2019-NM-149-AD" at the beginning of your comments.
The FAA specifically invites comments on the overall regulatory,
economic, environmental, and energy aspects of this NPRM. The FAA will
consider all comments received by the closing date and may amend this
NPRM because of those comments.
The FAA will post all comments, without change, to https://www.regulations
.gov, including any personal information you provide.
The FAA will also post a report summarizing each substantive verbal
contact the agency receives about this proposed AD.
The FAA issued AD 2012-21-08, Amendment 39-17224 (77 FR 64711,
October 23, 2012) ("AD 2012-21-08"), for certain The Boeing Company
Model 737-600, -700, -700C, -800, and -900 series airplanes. AD 2012-
21-08 requires inspecting for part numbers of the OPS of the FCCs and
installing and testing an updated version of the FCC OPS. AD 2012-21-08
resulted from reports of undetected erroneous output from a single
radio altimeter channel, which resulted in premature autothrottle
retard during approach. The FAA issued AD 2012-21-08 to address this
condition, which, if not detected and corrected, could result in the
loss of automatic speed control, and consequent loss of control of the
Actions Since AD 2012-21-08 Was Issued
Since the FAA issued AD 2012-21-08, the FAA has received reports
that during autopilot coupled Instrument Landing System (ILS)
approaches, the airplane did not capture or track the glideslope
correctly. This caused airplanes to continue descending below the
glideslope without any fault indication from the autopilot system. The
problems were reported with the autopilot engaged while attempting to
capture the glideslope from above, with a high descent rate greater
than 2,000 feet per minute and late arming of approach mode. The high
descent rate is maintained by the autopilot and can result in the
airplane descending below the glideslope beam, which requires the
flight crew to correct the problem manually. Boeing has developed an
upgrade to the FCC OPS for certain affected airplanes equipped with
Rockwell Collins FCCs that corrects the glideslope capture problem. The
FAA is proposing this AD to address this condition, which can result in
controlled flight into terrain on airplanes that do not have the
upgraded FCC OPS installed.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Boeing Alert Requirements Bulletin 737-22A1322 RB,
dated November 21, 2018. The service information describes procedures
for installing and testing an updated version of the FCC OPS.
This proposed AD would also require Boeing Alert Service Bulletin
737-22A1211, dated April 13, 2010, and Boeing Alert Service Bulletin 737-
22A1224, dated May 18, 2012, which the Director of the Federal Register
approved for incorporation by reference as of November 27, 2012 (77 FR
64711, October 23, 2012).
This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in the ADDRESSES section.
The FAA is proposing this AD because the FAA evaluated all the
relevant information and determined the unsafe condition described
previously is likely to exist or develop in other products of the same
Proposed AD Requirements
This proposed AD would retain certain requirements of AD 2012-21-
08. This proposed AD would expand the applicability of AD 2012-21-08 to
include The Boeing Company Model 737-900ER series airplanes. This
proposed AD would also require accomplishment of the actions specified
in the Accomplishment Instructions of Boeing Alert Requirements
Bulletin 737-22A1322 RB, dated November 21, 2018, described previously,
except as discussed under "Differences Between this Proposed AD and
the Service Information," and except for any differences identified as
exceptions in the regulatory text of this proposed AD.
For information on the procedures and compliance times, see this
service information at https://www.regulations.gov by searching for and
locating Docket No. FAA-2020-0103.
Explanation of Requirements Bulletin
The FAA worked in conjunction with industry, under the
Airworthiness Directive Implementation Aviation Rulemaking Committee
(AD ARC), to enhance the AD system. One enhancement is a process for
annotating which steps in the service information are "required for
compliance" (RC) with an AD. Boeing has implemented this RC concept
into Boeing service bulletins.
In an effort to further improve the quality of ADs and AD-related
Boeing service information, a joint process improvement initiative was
worked between the FAA and Boeing. The initiative resulted in the
development of a new process in which the service information more
clearly identifies the actions needed to address the unsafe condition
in the "Accomplishment Instructions." The new process results in a
Boeing Requirements Bulletin, which contains only the actions needed to
address the unsafe condition (i.e., only the RC actions).
Differences Between This Proposed AD and the Service Information
The effectivity of Boeing Alert Requirements Bulletin 737-22A1322
RB, dated November 21, 2018, is limited to The Boeing Company Model
737-600, -700, -700C, -800, -900, and 900ER series airplanes, line
numbers 1270, 1272, and 1278 through 7153 inclusive in one group.
Because the affected software versions are rotable among the airplanes
affected by this proposed AD, the FAA has determined that these parts
could later be installed on airplanes that were initially delivered
with acceptable software versions, thereby subjecting those airplanes
to the unsafe condition. Therefore, the applicability of this proposed
AD includes all The Boeing Company Model 737-600, -700, -700C, -800, -
900, and 900ER series airplanes. The FAA has confirmed with Boeing that
the Accomplishment Instructions in Boeing Alert Requirements Bulletin
737-22A1322 RB, dated November 21, 2018, are applicable to the expanded
group of airplanes.
Boeing Alert Requirements Bulletin 737-22A1322 RB, dated November
21, 2018, specifies that certain airplane line numbers must accomplish
an update of the FCC OPS. However, this AD requires that only airplanes
equipped with Rockwell Collins FCCs installed with FCC OPS version P8.0
or P9.0 must accomplish an update of the FCC OPS in accordance with the
Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-
22A1322 RB, dated November 21, 2018.
Costs of Compliance
The FAA estimates that this proposed AD affects 520 airplanes of
U.S. registry. The FAA estimates the following costs to comply with
this proposed AD:
Estimated Costs for Required Actions
|Inspection and installation (retained
actions from AD 2012-21-08)
||3 work-hours x $85 per hour =
$255 per inspection
|$52,785 (based on 207 affected
|Part number inspection (new proposed
||1 work-hour x $85 per hour =
The FAA estimates the following costs
to do any necessary on-
condition actions that would be required. The FAA has no way of
determining the number of aircraft that might need these on-condition
Estimated Costs of On-Condition Costs
|Install upgraded software
||1 work-hour x $85 per hour =
According to the manufacturer, all
of the costs of this proposed AD
may be covered under warranty, thereby reducing the cost impact on
affected individuals. The FAA does not control warranty coverage for
affected individuals. As a result, the FAA has included all costs in
our cost estimate.
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
The FAA has determined that this proposed AD would not have
federalism implications under Executive Order 13132. This proposed AD
would 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
For the reasons discussed above, I certify that the proposed
(1) Is not a "significant regulatory action" under Executive
(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
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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 removing Airworthiness Directive (AD)
2012-21-08, Amendment 39-17224 (77 FR 64711, October 23, 2012), and
adding the following new AD: