DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

14 CFR Part 39

[Docket No. 2002-CE-05-AD] RIN 2120-AA64

AIRWORTHINESS DIRECTIVES; Cessna Aircraft Company Models 401, 401A,  401B,
402, 402A, 402B, 411, and 411A Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to supersede Airworthiness Directive  (AD)
79-10-15 R2, which applies to all Cessna Aircraft Company (Cessna)  Models
401, 401A, 401B, 402, 402A, 402B, 411, and 411A airplanes. AD 79-10-15  R2
currently requires repetitive inspections of the right and left wing  spar
lower cap areas for  fatigue cracks and requires  wing spar cap repair  or
replacement as necessary.  Cessna has performed  fatigue and crack  growth
analyses  of  the  wings  of these  airplanes,  and  the  Federal Aviation
Administration (FAA) has evaluated this information and determined that  a
wing spar modification is necessary as well as periodic inspections.  This
proposed AD would require you  to repetitively inspect the wing  spar caps
for  fatigue  cracks  with  any necessary  repair  or  replacement  on all
airplanes and incorporate a spar  strap modification on each wing  spar on
certain airplanes. The actions specified by this proposed AD are  intended
to prevent wing  spar cap failure  due to undetected  fatigue cracks. Such
failure could result in  loss of a wing  with consequent loss of  airplane
control.

DATES: The Federal Aviation Administration (FAA) must receive any 
comments on this proposed rule on or before September 8, 2003. This is 
extended from August 8, 2003.

ADDRESSES: Submit comments to FAA, Central Region, Office of the  Regional
Counsel, Attention: Rules Docket No. 2002-CE-05-AD, 901 Locust, Room  506,
Kansas City, Missouri  64106. You may  view any comments  at this location
between 8 a.m. and 4 p.m., Monday through Friday, except Federal holidays.
You may also send comments electronically to the following address:  9-ACE
-7-Docket@faa.gov. Comments sent electronically must contain ``Docket  No.
2002-CE-05-AD'' in the subject  line. If you send  comments electronically
as attached  electronic files,  the files  must be  formatted in Microsoft
Word 97 for Windows or ASCII text.

You may get service information that applies to this proposed AD  from the
Cessna Aircraft  Company, Product Support,  PO Box 7706,  Wichita,  Kansas
67277; telephone: (316)   517-5800; facsimile: (316)  942-  9006. You  may
also view this information at the Rules Docket at the  address above.

FOR FURTHER  INFORMATION CONTACT:  Paul Nguyen,  Aerospace Engineer,  FAA,
Wichita Aircraft  Certification Office,  1801 Airport  Road, Mid-Continent
Airport,  Wichita,  Kansas 67209;  telephone:  (316) 946-4125;  facsimile:
(316) 946-4107.

SUPPLEMENTARY INFORMATION:

COMMENTS INVITED

How Do I Comment on This Proposed AD?

The FAA invites  comments on this  proposed rule. You  may submit whatever
written data,  views, or  arguments you  choose. You  need to  include the
rule's docket  number and  submit your  comments to  the address specified
under the caption ADDRESSES.

We will consider all comments received  on or before the closing date.  We
may  amend  this proposed  rule  in light  of  comments received.  Factual
information that supports your ideas and suggestions is extremely  helpful
in evaluating the effectiveness of this proposed AD action and determining
whether we need to take additional rulemaking action.

Are There Any Specific Portions of This Proposed AD I Should Pay Attention
to?

    The  FAA  specifically  invites comments  on  the  overall regulatory,
    economic, environmental, and energy aspects of this proposed rule that
    might suggest a need to modify the rule. You may view all comments  we
    receive before and  after the closing  date of the  rule in the  Rules
    Docket. We will file a report in the Rules Docket that summarizes each
    contact we have with the public that concerns the substantive parts of
    this proposed AD.

How Can I Be Sure FAA Receives My Comment?

    If you want  FAA to acknowledge  the receipt of  your mailed comments,
    you must include a self-addressed, stamped postcard. On the  postcard,
    write ``Comments to Docket No. 2002-CE-05-AD.'' We will date stamp and
    mail the postcard back to you.

DISCUSSION

Has FAA Taken Any Action to This Point?

    Reports of fatigue cracks on Cessna 401, 402, and 411 series airplanes
    caused FAA to take AD action  (AD 79-10-15 R2, Amendment 39- 3711)  to
    require repetitive inspections of the  right and left wing spar  lower
    cap areas for fatigue  cracks and to require  wing spar cap repair  or
    replacement as necessary.

    Accomplishment  of  the  inspections required  by  AD  79-10-15 R2  is
    required in accordance with Cessna Service Bulletin ME79-16,  Revision
    3, dated February 8, 1980.

    AD 79-10-15  R2 allowed  for the  incorporation of  Cessna Service Kit
    SK402-36 or SK411-56 on the  front wing spar lower cap  as terminating
    action for the repetitive inspections on the applicable wing.

What Has Happened Since AD 79-10-15 R2 To Initiate This Proposed Action?

    Since issuance of AD 79-10-15, Cessna has analyzed the wing, including
    fatigue and crack growth analyses, on the affected airplanes. Analysis
    included:

--A determination of  the probable location  and modes of  damage based on
analytical results, available test data, and service information;

--Classical fatigue analyses;

--Crack  growth and  residual strength  analyses including  use of  linear
elastic fracture mechanics methods;

--Full-scale ground testing to validate analytical models; and

--A flight strain survey to develop stress spectra used in the analyses.

    The inspections required by AD  79-10-15 R2 in accordance with  Cessna
    Service Bulletin ME79-16, Revision 3, are accomplished using a surface
    eddy current inspection method.

    Based on the analysis, Cessna  has found that the eddy  current method
    will not find the crack until it is .03 inch longer than the  critical
    crack length. When  the crack reaches  the critical length,  it is not
    reliably detectable because it is under the head of the fastener. Once
    the main spar cap is  severed, the remaining structure will  no longer
    meet the  residual strength  requirements. Wing  separation could then
    occur  under   loading  conditions   significantly  less   than  those
    established for the design limit load.

    Cessna reported only one instance where cracks were detected using the
    nondestructive  inspection  (NDI) eddy  current  procedure. There  are
    other reported instances  where cracks were  detected visually in  the
    wheel well area on the aft flange. The problem with visual inspections
    is the access doubler flanges cover a large percentage of the  forward
    spar flange. This limits the effectiveness of the visual inspections.

    To meet  industry NDI  standards, cracks  need to  be found  on Cessna
    Models  401, 401A,  401B, 402,  402A, 402B,  411, and  411A airplanes
    through  NDI  inspection  methods  with  a  90-percent  probability of
    detection at a 95-percent confidence level.

    Cessna's analysis indicates that the probability and confidence levels
    are not being met.

Is There Service Information That Applies to This Subject?

    Cessna has issued the following:

--Service Bulletin MEB01-06 and Service Kit SK402-46, both dated September
24, 2001; and

--Service Bulletin MEB01-07 and Service Kit SK411-59, both dated September
24, 2001.

    This  service  information  includes  procedures  for  inspecting  and
    modifying the lower wing spar caps.

The  FAA's Determination  and an  Explanation of  the Provisions  of This
Proposed AD

WHAT HAS FAA DECIDED?

    After  examining  the   circumstances  and  reviewing   all  available
    information  related  to  the  incidents  described  above,  we   have
    determined that:

--Cessna's analysis of  the problems with  the eddy current  inspection on
the wing spar cap area on the Cessna 401, 402, and 411 series airplanes is
valid;

--The unsafe condition referenced in this document exists or could develop
on these airplanes that are the same type design;

--The actions specified  in the previously-referenced  service information
should be accomplished on the affected airplanes; and

--AD action should be taken in order to correct this unsafe condition.

What Would This Proposed AD Require?

    This proposed AD  would supersede AD  79-10-15 R2 with  a new AD  that
    would require you to either (depending on the aircraft configuration):

--For airplanes  that do  not incorporate  one of  certain Cessna  Service
Kits:  repetitively inspect  the wing  spar caps  for fatigue  cracks and
repair or replace the wing spar  caps as necessary and incorporate a  spar
strap modification on each wing spar; or

--For  airplanes  that incorporate  one  of certain  Cessna  Service Kits:
repetitively inspect the wing spar  caps for fatigue cracks and  repair or
replace the wing spar caps as necessary.

How Does the Revision to 14 CFR Part 39 Affect This Proposed AD?

    On July 10, 2002, FAA published a new version of 14 CFR part 39 (67 FR
    47997, July 22, 2002), which governs FAA's AD system. This  regulation
    now  includes  material  that  relates  to  special  flight   permits,
    alternative methods of compliance, and altered products. This material
    previously was included in each individual AD. Since this material  is
    included  in 14  CFR part  39, we  will not  include it  in future  AD
    actions.

COST IMPACT

How Many Airplanes Would This Proposed AD Impact?

    We estimate that  this proposed AD  affects 400 airplanes  in the U.S.
    registry.

What Would Be the Cost Impact  of This Proposed AD on Owners/Operators  of
the Affected Airplanes?

    We  estimate   the  following   costs  to   accomplish  the   proposed
    modification and initial inspection:

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                                                           TOTAL COST  PER         TOTAL COST ON  U.S.
 LABOR COST                         PARTS COST                AIRPLANE                 OPERATORS
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485 workhours x $60 per hour =      $1,763 per airplane....  $29,100 + $1,763 =       $30,863 x 400 =
 $29,100 per airplane.                                          $30,863 per airplane.    $12,345,200.
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    The above  figures do  not take  into account  the cost  of repetitive
    inspections. The FAA does not  have any way of determining  the number
    of repetitive inspections each  owner/operator would incur during  the
    operating life of the affected airplanes.

REGULATORY IMPACT

Would This Proposed AD Impact Various Entities?

    The regulations proposed  herein 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 government. Therefore, it
    is  determined  that  this proposed  rule  would  not have  federalism
    implications under Executive Order 13132.

Would This Proposed AD Involve a Significant Rule or Regulatory Action?

    For the reasons discussed above,  I certify that this proposed  action
(1) is not a  ``significant regulatory action'' under  Executive Order
    12866; (2) is not a ``significant rule'' under DOT Regulatory Policies
    and  Procedures  (44  FR  11034,  February  26,  1979);  and  (3)   if
    promulgated, 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. A  copy of  the draft  regulatory
    evaluation  prepared for  this action  has been  placed in  the Rules
    Docket. A copy of it may be obtained by contacting the Rules Docket at
    the location provided under the caption ADDRESSES.

LIST OF SUBJECTS IN 14 CFR PART 39

    Air transportation, Aircraft, Aviation safety, Safety.

THE PROPOSED AMENDMENT

    Accordingly, under the authority delegated to me by the Administrator,
    the Federal Aviation Administration proposes  to amend part 39 of  the
    Federal Aviation Regulations (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. FAA amends Sec.  39.13 by removing Airworthiness Directive (AD)  79
    -10-15  R2, Amendment  39-3711, and  by adding  a new  AD to  read as
    follows: