[Federal Register Volume 61, Number 167 (Tuesday, August 27, 1996)]
[Proposed Rules]
[Pages 44002-44004]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-21743]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-53-AD]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series
Airplanes and Model MD-88 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain McDonnell Douglas Model
DC-9-80 series airplanes and Model MD-88 airplanes. This proposal would
require visual/dye penetrant and ultrasonic inspections to detect
cracks in the vertical leg of the rear spar lower cap of the wings, and
various follow-on actions. This proposal is prompted by reports that,
due to improper torque tightening of the attach studs of the flap hinge
fitting, fatigue cracks were found in the vertical leg of the rear spar
lower cap of the wing. The actions specified by the proposed AD are
intended to prevent such fatigue cracking, which, if not detected and
corrected in a timely manner, could result in loss of the spar cap, and
consequent damage to the spar cap web and adjacent wing skin structure;
this condition could lead to reduced structural integrity of the wing.
DATES: Comments must be received by October 7, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-53-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule may be
obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard,
Long Beach, California 90846, Attention: Technical Publications
Business Administration, Department C1-L51 (2-60). This information may
be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Brent Bandley, Aerospace Engineer,
Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification
Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone
(310) 627-5237; fax (310) 627-5210.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments
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submitted will be available, both before and after the closing date for
comments, in the Rules Docket for examination by interested persons. A
report summarizing each FAA-public contact concerned with the substance
of this proposal will be filed in the Rules Docket. Commenters wishing
the FAA to acknowledge receipt of their comments submitted in response
to this notice must submit a self-addressed, stamped postcard on which
the following statement is made: ``Comments to Docket Number 96-NM-53-
AD.'' The postcard will be date stamped and returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 96-NM-53-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports of fatigue cracks found in the
vertical leg of the rear spar lower cap of the wing on two McDonnell
Douglas Model MD-81 airplanes. One of the airplanes had accumulated
17,354 total landings, and the other airplane had accumulated
approximately 24,000 total landings. These fatigue cracks ran out of
the lower inboard attach stud hole for the inboard flap hinge fitting
of the outboard flap at station Xrs=164.000 on the left or right wings.
This fatigue cracking apparently is the result of applying less than
the required torque on the attach studs of the flap hinge fitting,
during production of these airplanes. Fatigue cracking in the vertical
leg of the rear spar lower cap of the wings, if not detected and
corrected in a timely manner, could result in loss of the spar cap, and
consequent damage to the spar cap web and adjacent wing skin structure;
this condition could lead to reduced structural integrity of the wing.
Explanation of Relevant Service Information
The FAA has reviewed and approved McDonnell Douglas MD-80 Service
Bulletin 57-184, Revision 1, dated December 22, 1994. The service
bulletin describes procedures for performing visual/dye penetrant and
ultrasonic inspections to detect cracks in the vertical leg of the rear
spar lower cap of the wings below and in the adjacent area of the two
lower attaching stud holes for the inboard hinge fitting of the
outboard flap at station Xrs=164.000. For cases where no cracks are
detected during inspection, the service bulletin describes procedures
for either tightening the four mounting studs of the flap hinge fitting
in the rear spar caps (two studs in the upper cap and two studs in the
lower cap) to applicable torque value, or conducting repetitive visual/
dye penetrant and ultrasonic inspections. For cases where any crack is
detected during the inspection, the service bulletin describes
procedures for performing a high frequency eddy current inspection to
confirm existence of cracking, and various follow-on actions. (These
follow-on actions include, among other actions, replacement of the
entire spar cap, permanent splice repair of the spar cap, temporary
repair of the spar cap, and repetitive inspections.)
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would require visual/dye penetrant and ultrasonic
inspections to detect cracks in the vertical leg of the rear spar lower
cap of the wings below and in the adjacent area of the two lower
attaching stud holes for the inboard hinge fitting of the outboard flap
at station Xrs=164.000, and various follow-on actions. The actions
would be required to be accomplished in accordance with the service
bulletin described previously. If any crack progression is found during
any repetitive eddy current inspection, the repair/replacement would be
required to be accomplished in accordance with a method approved by the
FAA.
Cost Impact
There are approximately 489 McDonnell Douglas Model DC-9-80 series
airplanes and Model MD-88 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 306 airplanes of U.S. registry
would be affected by this proposed AD, that it would take approximately
26 work hours per airplane to accomplish the proposed actions, and that
the average labor rate is $60 per work hour. Based on these figures,
the cost impact of the proposed AD on U.S. operators is estimated to be
$477,360, or $1,560 per airplane.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the proposed requirements of
this AD action, and that no operator would accomplish those actions in
the future if this AD were not adopted.
Regulatory Impact
The regulations proposed herein would not have substantial direct
effects 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, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the 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 is contained 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, pursuant to 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. Section 39.13 is amended by adding the following new
airworthiness directive:
McDonnell Douglas: Docket 96-NM-53-AD.
Applicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83
(MD-83), DC-9-87 (MD-87) series airplanes and Model MD-88 airplanes,
as listed in McDonnell Douglas MD-80 Service Bulletin 57-184,
Revision 1, dated December 22, 1994; certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the
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requirements of this AD is affected, the owner/operator must request
approval for an alternative method of compliance in accordance with
paragraph (e) of this AD. The request should include an assessment
of the effect of the modification, alteration, or repair on the
unsafe condition addressed by this AD; and, if the unsafe condition
has not been eliminated, the request should include specific
proposed actions to address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent fatigue cracking in the vertical leg of the rear spar
lower cap of the wing, which could lead to reduced structural
integrity of the wing, accomplish the following:
(a) Perform visual/dye penetrant and ultrasonic inspections to
detect cracks in the vertical leg of the rear spar lower cap of the
wings below and in the adjacent area of the two lower attaching stud
holes for the inboard hinge fitting of the outboard flap at station
Xrs=164.000, in accordance with McDonnell Douglas MD-80 Service
Bulletin 57-184, Revision 1, dated December 22, 1994; at the time
specified in paragraph (a)(1), (a)(2), (a)(3), or (a)(4) of this AD,
as applicable.
(1) For airplanes that have accumulated less than 8,000 total
landings as of the effective date of this AD: Perform the inspection
prior to the accumulation of 10,000 landings or within 3,000
landings after the effective date of this AD, whichever occurs
later.
(2) For airplanes that have accumulated 8,000 or more total
landings but less than 10,000 total landings as of the effective
date of this AD: Perform the inspection within 3,000 landings after
the effective date of this AD.
(3) For airplanes that have accumulated 10,000 or more total
landings but less than 15,000 total landings as of the effective
date of this AD: Perform the inspection within 2,400 landings after
the effective date of this AD.
(4) For airplanes that have accumulated 15,000 or more total
landings as of the effective date of this AD: Perform the inspection
within 1,800 landings after the effective date of this AD.
(b) Condition 1. If no crack is detected during any inspection
required by paragraph (a) of this AD, accomplish the requirements of
either paragraph (b)(1) or (b)(2) of this AD, in accordance with
McDonnell Douglas MD-80 Service Bulletin 57-184, Revision 1, dated
December 22, 1994.
(1) Condition 1, Option 1. Prior to further flight, tighten the
four mounting studs of the flap hinge fitting in the rear spar caps
(2 studs in the upper cap and 2 studs in the lower cap) to the
applicable torque value, in accordance with the service bulletin.
Accomplishment of this tightening of the mounting studs of the flap
hinge fitting constitutes terminating action for the repetitive
inspection requirements of paragraph (b)(2) of this AD.
(2) Condition 1, Option 2. Repeat the visual/dye penetrant and
ultrasonic inspections required by paragraph (a) of this AD
thereafter at intervals not to exceed 3,000 landings until paragraph
(b)(1) of this AD is accomplished.
(c) Condition 2. If any crack is detected during any inspection
required by paragraph (a) or (b)(2) of this AD, prior to further
flight, perform a high frequency eddy current inspection to confirm
the existence of cracking, in accordance with McDonnell Douglas MD-
80 Service Bulletin 57-184, Revision 1, dated December 22, 1994.
After this inspection, accomplish the requirements of either
paragraph (c)(1), (c)(2), or (c)(3) of this AD, as applicable.
(1) If no cracking is confirmed, accomplish the requirements of
either paragraph (b)(1) [``Condition 1, Option 1''] or (b)(2)
[``Condition 1, Option 2''] of this AD.
(2) Condition 2, Option 1. If any cracking is confirmed, prior
to further flight, replace the entire spar cap or accomplish the
permanent splice repair of the spar cap, and tighten the four
mounting studs of the flap hinge fitting in the rear spar caps (2
studs in the upper cap and 2 studs in the lower cap) to the
applicable torque value, in accordance with the service bulletin.
Accomplishment of this tightening of the mounting studs constitutes
terminating action for the repetitive inspection requirements of
paragraph (c)(3) of this AD.
(3) Condition 2, Option 2. If cracking is confirmed and it does
not extend beyond the location limits and does not exceed the
maximum permissible crack length of 2 inches, prior to further
flight, accomplish the temporary repair modification of the spar cap
in accordance with the service bulletin. Thereafter, repeat the eddy
current inspection at intervals not to exceed 3,000 landings until
paragraph (c)(2) of this AD is accomplished.
(i) If any crack progression is found during any repetitive eddy
current inspection following accomplishment of the temporary repair,
prior to further flight, contact the Manager, Los Angeles Aircraft
Certification Office, FAA, Transport Airplane Directorate, telephone
(310) 627-5237, fax (310) 627-5210, to establish the appropriate
repair or replacement interval.
Note 2: Operators should note that, unlike the recommended
compliance time of ``within 3,000 landings after discovery of
cracking,'' which is specified in the service bulletin as the time
for accomplishing the permanent splice repair or replacement of the
spar cap, this AD requires that operators contact the FAA prior to
further flight. The FAA finds that the repair/replacement interval
should be established based on the crack progression. Where there
are differences between the AD and the service bulletin in this
regard, the AD prevails.
(ii) If any new crack is found during any repetitive eddy
current inspection following accomplishment of the temporary repair,
prior to further flight, accomplish the permanent repair in
accordance with the service bulletin.
(d) Within 10 days after accomplishing the initial visual/dye
penetrant and ultrasonic inspections required by paragraph (a) of
this AD, submit a report of the inspection results (both positive
and negative findings) to the Manager, Los Angeles ACO, 3229 East
Spring Street, Long Beach, California 90806-2425; telephone (310)
627-5237; fax (310) 627-5210. Information collection requirements
contained in this regulation have been approved by the Office of
Management and Budget (OMB) under the provisions of the Paperwork
Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been
assigned OMB Control Number 2120-0056.
(e) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Los Angeles Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Los Angeles ACO.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(f) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
Issued in Renton, Washington, on August 20, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-21743 Filed 8-26-96; 8:45 am]
BILLING CODE 4910-13-U
