[Federal Register Volume 62, Number 17 (Monday, January 27, 1997)]
[Rules and Regulations]
[Pages 3781-3784]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1438]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-01-AD; Amendment 39-9895; AD 97-02-10]
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: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to certain McDonnell Douglas Model DC-9, DC-9-80, and C-9
(military) series airplanes, Model MD-88 airplanes, and Model MD-90
airplanes. This action 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 modification of the NLG.
This action also provides for terminating action for the repetitive
inspections. This amendment is 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
actions specified in this 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.
DATES: Effective February 11, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of February 11, 1997.
Comments for inclusion in the Rules Docket must be received on or
before March 28, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 97-NM-01-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056.
The service information referenced in this AD may be obtained from
McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach,
[[Page 3782]]
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; or at the FAA, Transport Airplane Directorate,
Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard,
Lakewood, California; or at the Office of the Federal Register, 800
North Capitol Street, NW., suite 700, Washington, DC.
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: The FAA has recently received a report
indicating that the upper lock link assembly of the nose landing gear
(NLG) on a McDonnell Douglas DC-9-80 series airplane failed prior to
landing. As a result of this failure, the airplane sustained moderate
damage to the forward lower fuselage.
An investigation by the operator revealed that this assembly had
fractured and jammed against the shock strut, which prevented the NLG
from extending fully. This fracture was caused by fatigue cracking that
originated at the lower end of the assembly where the flange and inner
radius meet. The operator also detected similar fatigue cracking in two
other upper lock link assemblies during an inspection of other
airplanes in its fleet.
An upper lock link assembly can be either manufactured from
aluminum plate or forged from aluminum. The three cracked assemblies
that were detected were aluminum plate, a material which has a much
shorter fatigue life than forged aluminum. In addition to Model DC-9-80
series airplanes, assemblies of aluminum plate may be installed on
Model DC-9 and C-9 (military) series airplanes, Model MD-88 airplanes,
and Model MD-90 airplanes.
Fracturing of the upper lock link assembly due to fatigue cracking,
if not corrected, can result in the failure of the NLG to extend fully,
which could lead to injury to passengers and flight crew, and damage to
the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved McDonnell Douglas Alert Service
Bulletin DC9-32A298 [for Model DC-9, DC-9-80, and C-9 (military) series
airplanes, and Model MD-88 airplanes], and McDonnell Douglas Alert
Service Bulletin MD90-32A019 [for Model MD-90 airplanes], both dated
December 19, 1996. Both alert service bulletins describe procedures for
conducting a visual check of the part number and serial number on the
upper lock link assembly of the NLG to identify whether an assembly has
been forged from aluminum (an ``exempt upper lock link assembly''), or
has been manufactured from aluminum plate (a ``possible discrepant
upper lock link assembly''). No further action is necessary if an
exempt upper lock link assembly is installed.
Both alert service documents also describe procedures for
conducting repetitive high frequency eddy current inspections or Type I
fluorescent penetrant inspections to detect fatigue cracking in a
possible discrepant upper lock link assembly. When fatigue cracking is
detected in this upper lock link assembly or when the assembly's safe
life (46,500 cycles of the NLG) has been reached, the pin assembly of
the NLG is to be replaced with a new or serviceable pin assembly. (The
upper lock link assembly is contained within the pin assembly.) If the
pin assembly is replaced with one that contains an exempt upper lock
link assembly, the need for subsequent repetitive inspections and
replacement of parts is eliminated.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other McDonnell Douglas Model DC-9, DC-9-80, and C-
9 (military) series airplanes, Model MD-88 airplanes, and Model MD-90
airplanes, of the same type design, this AD is being issued to prevent
fracturing of the upper lock link assembly due to fatigue cracking, and
the consequent failure of the NLG to extend fully, which could lead to
injury to passengers and flight crew, and damage to the airplane.
This AD requires a visual check of the part number and serial
number on the upper lock link assembly to identify whether this
assembly is a possible discrepant assembly or an exempt assembly. (No
further action is required if an upper lock link assembly is an exempt
assembly.)
This AD also requires repetitive high frequency eddy current
inspections or Type I fluorescent penetrant inspections of any possible
discrepant upper lock link assembly to detect fatigue cracking. When
fatigue cracking is detected in the upper lock link assembly, this AD
requires that the pin assembly of the NLG be replaced with a new or
serviceable pin assembly. The operator, at its option, may install a
replacement pin assembly that contains an exempt, rather than a
possible discrepant, upper lock link; this substitution terminates the
requirement for repetitive inspections.
The actions are required to be accomplished in accordance with the
applicable alert service bulletin described previously.
Interim Action
This is considered to be interim action. The manufacturer has
advised that it currently is developing a modification that will
positively address the unsafe condition addressed by this AD. Once this
modification is developed, approved, and available, the FAA may
consider additional rulemaking.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the 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 that
summarizes each FAA-public contact
[[Page 3783]]
concerned with the substance of this AD will be filed in the Rules
Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 97-NM-01-AD.'' The postcard will be date stamped and
returned to the commenter.
Regulatory Impact
The regulations adopted herein will 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 final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, may be obtained from the Rules Docket at the
location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends 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:
97-02-10 McDonnell Douglas: Amendment 39-9895. Docket 97-NM-01-AD.
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 [for
Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model
MD-88 airplanes], and McDonnell Douglas Alert Service Bulletin MD90-
32A019 [for Model MD-90 airplanes], both dated December 19, 1996;
certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise 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 (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 fracturing of the upper lock link assembly of the
nose landing gear (NLG) due to fatigue cracking, and the consequent
failure of the NLG to extend fully, which could lead to injury to
passengers and flight crew, and damage to the airplane, accomplish
the following:
(a) 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, conduct a visual check of the upper lock link assembly
of the NLG to determine its part and serial number, in accordance
with McDonnell Douglas Alert Service Bulletin DC9-32A298 [for Model
DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-88
airplanes], or McDonnell Douglas Alert Service Bulletin MD90-32A019
[for Model MD-90 airplanes], both dated December 19, 1996, as
applicable.
(b) If the part number and serial number of the upper lock link
assembly are listed in paragraph (b)(1) or (b)(2) of this AD (``an
exempt upper lock link assembly''), no further action is required.
Note 2: An ``exempt upper lock link assembly'' as specified in
paragraph (b) of this AD is an assembly that is manufactured of
forged aluminum.
(1) For Model DC-9, DC-9-80, and C-9 (military) series
airplanes, and Model MD-88 airplanes: Part Number (P/N) 3914464-(any
configuration) having serial numbers (S/N) HMI001 through HMI172
inclusive, or S/N WPI1000 and subsequent; or P/N 5920472-(any
configuration) having any serial number.
(2) For Model MD-90 airplanes: P/N 3914464-503 having S/N HMI001
through HMI172 inclusive, or S/N WPI1000 and subsequent.
(c) If the part number and serial number of the upper lock link
assembly are not listed in paragraph (b)(1) or (b)(2) of this AD ( a
``possible discrepant upper lock link assembly''), except as
provided by paragraph (c)(3) of this AD, prior to further flight,
conduct either a high frequency eddy current inspection or a Type I
fluorescent penetrant inspection of this assembly to detect fatigue
cracks, in accordance with McDonnell Douglas Alert Service Bulletin
DC9-32A298 [for Model DC-9, DC-9-80, and C-9 (military) series
airplanes, and Model MD-88 airplanes], or McDonnell Douglas Alert
Service Bulletin MD90-32A019 [for Model MD-90 airplanes], both dated
December 19, 1996.
Note 3: A ``possible discrepant upper lock link assembly'' as
specified in paragraph (c) of this AD is an assembly that may be
manufactured from aluminum plate.
(1) If no crack is detected, repeat either type of inspection
required by paragraph (c) of this AD at intervals not to exceed
5,000 cycles of the NLG.
(2) If any crack is detected, prior to further flight, replace
the pin assembly of the NLG in accordance with the applicable alert
service bulletin.
(3) A Type I fluorescent penetrant inspection of the upper lock
link assembly that has been conducted within the last 12 months
prior to the effective date of this AD and in accordance with the
DC-9 Overhaul Manual or MD-90 Component Manual, Chapter 20-70-2, is
considered acceptable for compliance with the initial inspection
required by paragraph (c) of this AD. If no crack was detected
during that inspection, subsequent repetitive inspections are
required to be accomplished at the intervals specified in paragraph
(c)(1) of this AD.
(d) When replacement of the pin assembly of the NLG is required
in accordance with paragraph (c)(1) or (c)(2) of this AD:
(1) If the pin assembly is replaced with a new assembly that
contains a possible discrepant upper lock assembly: After the pin
assembly has been replaced, repeat the inspection required by
paragraph (c) of this AD prior to the accumulation of 10,000 cycles
of the NLG.
(2) If the pin assembly is replaced with a serviceable assembly
that contains a possible discrepant upper lock assembly: After the
pin assembly has been replaced, repeat the inspection required by
paragraph (c) of this AD either prior to the accumulation of 10,000
total cycles of the NLG for that pin assembly, or prior to further
flight, whichever occurs later.
(3) If the pin assembly is replaced with a pin assembly that
contains an exempt upper lock link assembly: No further action is
required. This installation constitutes terminating action for the
repetitive inspections required by this AD.
(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
[[Page 3784]]
an appropriate FAA Principal Maintenance Inspector, who may add
comments and then send it to the Manager, Los Angeles ACO.
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.
(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.
(g) The visual check, repetitive inspections, and replacement of
the pin assembly of the NLG shall be done in accordance with
McDonnell Douglas Alert Service Bulletin DC9-32A298, dated December
19, 1996; or McDonnell Douglas Alert Service Bulletin MD90-32A019,
dated December 19, 1996; as applicable. This incorporation by
reference was approved by the Director of the Federal Register in
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be
obtained from McDonnell Douglas Corporation, 3855 Lakewood
Boulevard, Long Beach, California 90846, Attention: Technical
Publications Business Administration, Department C1-L51 (2-60).
Copies may be inspected 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; or at the Office of
the Federal Register, 800 North Capitol Street, NW., suite 700,
Washington, DC.
(h) This amendment becomes effective on February 11, 1997.
Issued in Renton, Washington, on January 14, 1997.
S. R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-1438 Filed 1-24-97; 8:45 am]
BILLING CODE 4910-13-P
