[Federal Register Volume 64, Number 198 (Thursday, October 14, 1999)]
[Proposed Rules]
[Pages 55644-55648]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26872]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-298-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, 
and C-9 (Military) Series Airplanes; Model MD-88 Airplanes; and Model 
MD-90 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain McDonnell Douglas 
Model DC-9, DC-9-80, and C-9 (military) series airplanes; Model MD-88 
airplanes; and MD-90 airplanes, that currently requires a visual check 
to determine the part and serial numbers of the upper lock link 
assembly of the nose landing gear (NLG); repetitive inspections of 
certain upper lock link assemblies to detect fatigue cracking; and 
replacement of the upper lock link assembly with an assembly made from 
aluminum forging material, if necessary. Such replacement would 
constitute terminating action for the requirements of this AD. The 
proposed AD would expand the

[[Page 55645]]

applicability of the existing AD, reduce the compliance times for the 
inspections, and add new inspection requirements. This proposal is 
prompted by a report indicating that an NLG upper lock link fractured 
prior to landing and jammed against the NLG shock strut, restricting 
the NLG from fully extending. The actions specified by this proposal 
are intended to prevent the upper lock link assembly from fracturing 
due to fatigue cracking, and the NLG consequently failing to extend 
fully; this condition could result in injury to passengers and flight 
crew, and damage to the airplane.

DATES: Comments must be received by November 29, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-298-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 Boeing Commercial Aircraft Group, Long Beach Division, 
3855 Lakewood Boulevard, Long Beach, California 90846, Attention: 
Technical Publications Business Administration, Dept. C1-L51 (2-60). 
This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, 
Transport Airplane Directorate, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT: Brent Bandley, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712-4137; telephone (562) 627-5237; fax (562) 
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 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 97-NM-298-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-114, Attention: Rules 
Docket No. 97-NM-298-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On January 14, 1997, the FAA issued AD 97-02-10, amendment 39-9895 
(62 FR 3781, January 27, 1997), applicable to certain McDonnell Douglas 
Model DC-9, DC-9-80, and C-9 (military) series airplanes; Model MD-88 
airplanes; and MD-90 airplanes. That AD requires a visual check to 
determine the part and serial numbers of the upper lock link assembly 
of the nose landing gear (NLG); repetitive inspections of certain upper 
lock link assemblies to detect fatigue cracking; and replacement of the 
upper lock link assembly with an assembly made from aluminum forging 
material, if necessary. That action was prompted by a report indicating 
that, due to fatigue cracking, the upper lock link assembly on an 
airplane fractured, and consequently prevented the NLG from extending 
fully. The requirements of that AD are intended to prevent this 
assembly from fracturing due to fatigue cracking, and the NLG 
consequently failing to extend fully; this condition could result in 
injury to passengers and flight crew, and damage to the airplane.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 97-02-10, the FAA has received one report 
of an incident involving a McDonnell Douglas Model DC-9-82 (MD-82) 
series airplane in which the upper lock link failed and the NLG 
collapsed on landing. In addition, the FAA has received reports of 
three lock link failures and four cracked lock links.
    In the preamble to AD 97-02-10, the FAA specified that the actions 
required by that AD were considered ``interim action'' and that the 
manufacturer was developing a modification to positively address the 
unsafe condition. The FAA indicated that it may consider further 
rulemaking action once the modification was developed, approved, and 
available. The manufacturer now has developed a method that can be used 
by the operators to identify the type of material used for the upper 
lock link (overcenter link) of the NLG, and the FAA has determined that 
further rulemaking action is indeed necessary. This proposed AD follows 
from that determination.

Additional Relevant Service Information

    The FAA has reviewed and approved the following McDonnell Douglas 
Service Bulletins, both dated March 11, 1999:
     MD90-32-033 (for Model MD-90 airplanes).
     DC9-32-315 [for Model DC-9, DC-9-80, and C-9 (military) 
series airplanes; and Model MD-88 airplanes].
    Those service bulletins specify procedures for removing and 
retaining certain upper lock links and attaching parts for the NLG, and 
a visual inspection of the NLG upper lock link assembly to determine 
whether the assembly is from the affected lot specified in the 
applicable service bulletin. Procedures also include the following on-
condition actions:
     If the link is from the affected lot, replace the link 
with either a new upper lock link or a lock link assembly made from 
aluminum forging material.
     If the upper lock link is not from the affected lot, etch 
inspect to determine the type of material used for the lock link 
(Condition 2 or 3). If an NLG upper lock link is made from aluminum 
forging material (Condition 2), reidentify the lock link by adding an 
``F'' to the P/N. If an NLG upper lock link is made from plate or bar 
material (Condition 3), accomplish either of two options. Option 1 
specifies permanently removing any discrepant lock link and replacing 
it with a new upper lock link or a lock link assembly made from 
aluminum forging. Option 2 specifies restoring the link finish; 
reidentifying the lock link by adding a paint stripe next to the part 
number, which indicates the part is not made from aluminum forging 
material; and eventually replacing the upper lock link assembly with a 
link made from aluminum forging material.

[[Page 55646]]

    The FAA also has reviewed and approved the following McDonnell 
Douglas Alert Service Bulletins, both dated October 29, 1997.
     MD90-32A019, Revision 02 (for Model MD-90 airplanes).
     DC9-32A298, Revision 02 [for Model DC-9, DC-9-80, and C-9 
(military) series airplanes; and Model MD-88 airplanes].
    Those alert service bulletins are essentially the same as the 
earlier versions of the service bulletins, which include procedures for 
a high frequency eddy current inspection and Type I fluorescent 
penetrant inspection of the upper lock link to detect cracking of the 
lock link. However, Revision 02 adds airplanes to the effectivity and 
reduces the compliance times for the inspections.
    Accomplishment of the actions specified in the applicable service 
bulletin referenced above is intended to adequately address the 
identified unsafe condition.

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 supersede AD 97-02-10 to continue to require an 
inspection to determine the part and serial numbers of the upper lock 
link assembly of the NLG. This proposed AD would expand the 
applicability of the existing AD, reduce the compliance times for the 
inspections, and add new inspection requirements. The proposed AD also 
requires replacement of the NLG upper lock link, if necessary. Such 
replacement would constitute terminating action for the requirements of 
this AD.
    The actions would be required to be accomplished in accordance with 
the previously referenced service information.

Explanation of Proposed Compliance Times

    Based on further investigation, the FAA finds that the current 
inspection thresholds and intervals for the repetitive inspections 
specified by AD 97-02-10 are inadequate to detect cracking in a timely 
manner. Consequently, it is necessary to lower the threshold for the 
one-time inspections of the upper lock link assembly of the NLG, and to 
require replacement actions in lieu of repetitive inspections.
    The FAA has determined the compliance times for the one-time 
inspections for the proposed rule based on calculations of the fatigue 
life of the lock link made from plate or bar material and crack growth 
analysis, and has taken into account the detectability of the non-
destructive inspection methods used. The shorter compliance times were 
determined because of findings of higher stress levels in the NLG upper 
lock link than previously indicated due to increased crack growth rate 
beyond the initial inspection threshold.
    AD 97-02-10 requires that the initial inspection of the upper lock 
link assembly of the NLG be accomplished ``prior to the accumulation of 
10,000 total cycles of the NLG, or within 90 days after the effective 
date of this AD, whichever occurs later.'' However, paragraphs (a) and 
(b) of this proposed rule would require a one-time detailed visual 
inspection of the NLG upper lock link assembly to be accomplished 
``within 2,500 landings on the NLG after the effective date of this AD, 
or 5,000 landings since the last inspection accomplished in accordance 
with paragraph (a) of AD 97-02-10, whichever occurs first.''

Clarification of Requirements

    The FAA has determined that it is necessary to clarify certain 
terminology used in AD 97-02-10. In light of this, the term ``visual 
check'' has been changed to ``detailed visual inspection'' in this AD. 
The FAA considers that this type of inspection is necessary to ensure 
the continued operational safety of the fleet.

Differences Between Proposed Rule and Service Information

    Operators should note that, although the previously referenced 
service bulletins specify repetitive inspections of the upper lock link 
for cracks, this proposed AD does not require repetitive inspections.
    The FAA has determined that long term continued operational safety 
will be better assured by modifications or design changes to remove the 
source of the problem, rather than by repetitive inspections. Long term 
inspections may not be providing the degree of safety assurance 
necessary for the transport airplane fleet. This, coupled with a better 
understanding of the human factors associated with numerous repetitive 
inspections, has led the FAA to consider placing less emphasis on 
special procedures and more emphasis on design improvements. The 
proposed replacement requirement is in consonance with these 
considerations.
    Operators also should note that Boeing Alert Service Bulletins 
MD90-32A019 and DC9-32A298, both Revision 02, specify procedures for 
``exempt and non-exempt'' lock link assemblies. However, in this 
proposed AD there are no lock link assemblies specified as ``exempt or 
non-exempt.'' Instead, a one-time detailed visual inspection is 
required to determine whether the upper lock link assembly is from an 
``affected lot,'' as specified in Boeing Service Bulletin MD90-32-033 
or DC9-32-315.

Cost Impact

    There are approximately 2,100 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,400 airplanes of U.S. 
registry would be affected by this proposed AD.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed detailed visual and etch inspections of the NLG upper lock 
link, at an average labor rate of $60 per work hour. Based on these 
figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $84,000, or $60 per airplane.
    It would take approximately 2 work hours per airplane to accomplish 
each proposed replacement of the NLG upper lock link, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $5,803 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be 
$8,292,200, or $5,923 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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

[[Page 55647]]

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 removing amendment 39-9895 (62 FR 
3781, January 27, 1997), and by adding a new airworthiness directive 
(AD), to read as follows:

McDonnell Douglas: Docket 97-NM-298-AD. Supersedes AD 97-02-10, 
Amendment 39-9895.

    Applicability: Model DC-9, DC-9-80, and C-9 (military) series 
airplanes; Model MD-88 airplanes; and Model MD-90 airplanes; as 
listed in McDonnell Douglas Alert Service Bulletins DC9-32A298, and 
MD90-32A019, both Revision 02, dated October 29, 1997; 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 requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (d)(1) 
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 the upper lock link assembly of the nose 
landing gear (NLG) from fracturing due to fatigue cracking, and the 
NLG consequently failing to extend fully, which could result in 
injury to passengers and flight crew, and damage to the airplane, 
accomplish the following:

Removing and Retaining Upper Lock Link

    (a) Within 2,500 landings on the NLG after the effective date of 
this AD, or 5,000 landings since the last inspection accomplished in 
accordance with paragraph (a) of AD 97-02-10, whichever occurs 
first, remove and retain the upper lock link, part number (P/N) 
3914464, and attaching parts; and accomplish the inspections 
required by paragraphs (b) and (c) of this AD, in accordance with 
McDonnell Douglas Service Bulletin DC9-32-315 [for Model DC-9, DC-9-
80, and C-9 (military) series airplanes; and Model MD-88 airplanes], 
or McDonnell Douglas Service Bulletin MD90-32-033 (for Model MD-90 
airplanes), both dated March 11, 1999; as applicable.

Detailed Visual Inspection

    (b) Perform a one-time detailed visual inspection of the NLG 
upper lock link assembly to determine whether the serial number of 
the lock link is identified in the affected lot specified in 
Condition 1 of the Accomplishment Instructions of the applicable 
service bulletin, in accordance with McDonnell Douglas Service 
Bulletin DC9-32-315 [for Model DC-9, DC-9-80, and C-9 (military) 
series airplanes; and Model MD-88 airplanes], or McDonnell Douglas 
Service Bulletin MD90-32-033 (for Model MD-90 airplanes), both dated 
March 11, 1999; as applicable.

Identifying Upper Lock Links From Affected Lot and Corrective Actions:

Condition 1 (Hand Forging Serial Number)

    (1) If the serial number of the upper lock link is not from the 
affected lot specified in the applicable service bulletin (Condition 
1), prior to further flight, accomplish the etch inspection required 
by paragraph (c) of this AD, in accordance with the applicable 
service bulletin.
    (2) If the serial number of the upper lock link is from the 
affected lot specified in the applicable service bulletin (Condition 
1), prior to further flight, replace the lock link with a new upper 
lock link, P/N 3914464-507; a reidentified upper lock link, P/N 
3914464; or a new upper lock link assembly, P/N 5965065-507; all 
made from aluminum forging material; in accordance with the 
applicable service bulletin. Accomplishment of the replacement 
action constitutes terminating action for the requirements of this 
AD.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at an 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirrors, magnifying lenses, etc. may be used. Surface cleaning 
and elaborate access procedures may be required.''

Etch Inspection

    (c) Perform a one-time etch inspection of the NLG upper lock 
link to determine whether the lock link is made from aluminum 
forging material (Condition 2), or from plate or bar material 
(Condition 3), in accordance with McDonnell Douglas Service Bulletin 
DC9-32-315 [for Model DC-9, DC-9-80, and C-9 (military) series 
airplanes; and Model MD-88 airplanes], or McDonnell Douglas Service 
Bulletin MD90-32-033 (for Model MD-90 airplanes), both dated March 
11, 1999; as applicable.

Corrective Actions

Condition 2 (Aluminum Forging Material)

    (1) If the upper lock link is made from aluminum forging 
material, prior to further flight, restore the finish and reidentify 
the lock link, P/N 3914464, by adding an ``F'' to the part number, 
using an electro etch method, in accordance with the applicable 
service bulletin. Following accomplishment of the identification of 
the lock link as being made from aluminum forging material, no 
further action is required by this AD.

Condition 3 (Plate or Bar Material)

    (2) If the NLG upper lock link is made from plate or bar 
material, prior to further flight, accomplish either Option 1, as 
specified by paragraph (c)(2)(i) of this AD, or Option 2, as 
specified by paragraphs (c)(2)(ii) and (c)(2)(iii) of this AD.

Option 1

    (i) Permanently remove any discrepant upper lock link and 
replace with a new upper lock link, P/N 3914464-507; a reidentified 
upper lock link, P/N 3914464; or a new upper lock link assembly, P/N 
5965065-507; all made from aluminum forging material; in accordance 
with the applicable service bulletin. Accomplishment of the 
replacement action constitutes terminating action for the 
requirements of this AD.

Option 2

    (ii) Restore the link finish and reidentify the upper lock link 
by adding a paint stripe adjacent to the part number, indicating 
that the part is not made from aluminum forging material; in 
accordance with the applicable service bulletin.
    (iii) Perform a high frequency eddy current inspection (HFEC) 
and Type I fluorescent penetrant inspection of the upper lock link 
assembly, P/N 3914464-(any configuration), to detect cracking of the 
assembly, in accordance with McDonnell Douglas Alert Service 
Bulletin DC9-32A298, Revision 02 [for Model DC-9, DC-9-80, and C-9 
(military) series airplanes; and Model MD-88 airplanes], or Alert 
Service Bulletin MD90-32A019, Revision 02 (for Model MD-90 
airplanes), both dated October 29, 1997; as applicable.

    Note 3: Accomplishment of the inspections of the upper lock link 
assembly of the NLG, as specified by paragraph (c)(2)(iii) of this 
AD, prior to the effective date of this AD, in accordance with 
McDonnell Douglas Alert Service Bulletins DC9-32A298, dated December 
19, 1996, or Revision 01, dated June 16, 1997; or MD90-32A019, dated 
December 19, 1996, or Revision 01, dated June 16, 1997; as 
applicable; is considered acceptable for compliance with the 
inspection requirements of paragraph (c)(2)(iii) of this AD.

Replacement

    (A) If no crack is detected during the inspections required by 
paragraph (c)(2)(iii)

[[Page 55648]]

of this AD, within 2,500 landings on the NLG since accomplishment of 
the inspection performed in accordance with paragraph (c)(2)(iii) of 
this AD, replace the upper lock link with a new upper lock link, P/N 
3914464-507; a reidentified upper lock link, P/N 3914464; or a new 
upper lock link assembly, P/N 5965065-507; all made from aluminum 
forging material; in accordance with McDonnell Douglas Service 
Bulletin DC9-32-315 [for Model DC-9, DC-9-80, and C-9 (military) 
series airplanes; and Model MD-88 airplanes], or McDonnell Douglas 
Service Bulletin MD90-32-033 (for Model MD-90 airplanes), both dated 
March 11, 1999; as applicable. Accomplishment of the replacement 
action constitutes terminating action for the requirements of this 
AD.
    (B) If any crack is detected during the inspections required by 
paragraph (c)(2)(iii) of this AD, prior to further flight, replace 
the discrepant NLG upper lock link with a new upper lock link, P/N 
3914464-507; a reidentified upper lock link, P/N 3914464; or a new 
upper lock link assembly, P/N 5965065-507; all made from aluminum 
forging material; in accordance with the applicable service 
bulletin. Accomplishment of the replacement action constitutes 
terminating action for the requirements of this AD.

Alternative Methods of Compliance

    (d)(1) 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.
    (d)(2) Alternative methods of compliance, approved previously in 
accordance with AD 97-02-10, amendment 39-9895, are approved as 
alternative methods of compliance with paragraph (d)(1) of this AD.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

Special Flight Permits

    (e) 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 October 7, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-26872 Filed 10-13-99; 8:45 am]
BILLING CODE 4910-13-U