[Federal Register Volume 63, Number 194 (Wednesday, October 7, 1998)]
[Rules and Regulations]
[Pages 53800-53802]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-26821]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-47-AD; Amendment 39-10820; AD 98-21-12]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Helicopter Systems 
Model 369D, 369E, 369FF, 500N, AH-6, and MH-6 Helicopters

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 McDonnell Douglas Helicopter Systems (MDHS) Model 
369D, 369E, 369FF, 500N, AH-6 and MH-6 helicopters. This action 
requires visual inspections of the overrunning clutch retainer, 
carrier, housing, and pin for wear from spinning of the bearing outer 
race. This amendment is prompted by a report of inflight vibrations and 
subsequent investigations of three other overrunning clutches, which 
indicated wear of the bearing carrier due to spinning of the bearing 
outer race. The actions specified in this AD are intended to detect 
wear of other clutch components, excessive vibration which could lead 
to failure of the overrunning clutch, wear on the bearing carrier, and 
subsequent loss of power to the helicopter rotor drive system.

DATES: Effective October 22, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 22, 1998.
    Comments for inclusion in the Rules Docket must be received on or 
before December 7, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 97-SW-47-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.
    The service information referenced in this AD may be obtained from 
McDonnell Douglas Helicopter Systems, Field Service Department, 5000 E. 
McDowell Road, Mesa, Arizona, telephone (800) 388-3378, fax (602) 891-
6782. This information may be examined at the FAA, Office of the 
Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort 
Worth, Texas 76137; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. Bruce Conze, Aerospace Engineer, 
FAA, Los Angeles Aircraft Certification Office, 3960 Paramount 
Boulevard, Lakewood, California 90712, telephone (562) 627-5261, fax 
(562) 627-5210.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is 
applicable to MDHS Model 369D, 369E, 369FF, 500N, AH-6, and MH-6 
helicopters. This action requires a visual inspection of the 
overrunning clutch retainer, part number (P/N) 369F5460-1, carrier, P/N 
369F5461-1, housing, P/N 369F5451-1, and pin, P/N MS16556-801, for wear 
due to spinning of the bearing retainer and the outer race of the 
bearing. This amendment is prompted by a report of an operator that 
experienced inflight vibrations. Subsequent investigation revealed that 
the bearing retainer and the outer race of the bearing were spinning, 
which led to wear of the bearing carrier and movement of the bearing 
outer race. Investigations of three other overrunning clutches with the 
same P/N also indicated there had been spinning of the retainer. This 
condition, if not corrected, could result in wear on the bearing 
carrier, which could lead to failure of the overrunning clutch, 
excessive vibration, wear of other clutch components, and subsequent 
loss of power to the helicopter rotor drive system.
    The FAA has reviewed MDHS Service Information Notice No. DN-190, 
EN-83, FN-70, NN-011, dated July 25, 1997, which describes procedures 
for visually inspecting the overrunning clutch

[[Page 53801]]

retainer, carrier, and pin for clutch or carrier wear, or pin damage, 
and replacing any unairworthy clutch assembly with an airworthy clutch 
assembly.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other MDHS Model 369D, 369E, 369FF, 500N, AH-6, and 
MH-6 helicopters of the same type design, this AD is being issued to 
detect wear of other clutch components, excessive vibration which could 
lead to failure of the overrunning clutch, wear on the bearing carrier, 
and subsequent loss of power to the helicopter rotor drive system. This 
AD requires visual inspections of the overrunning clutch retainer, 
carrier, housing, and pin, for wear from spinning of the bearing 
retainer. The actions are required to be accomplished in accordance 
with the service information notice described previously.
    The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
controllability of the helicopter. Therefore, inspections of the 
overrunning clutch components is required within 25 hours time-in-
service (TIS) and this AD must be issued immediately.
    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.
    The FAA estimates that 2,200 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 2 work hours to 
accomplish the inspection and 14 work hours to accomplish either the 
replacement of components, or replacement the entire clutch assembly, 
and that the average labor rate is $60 per work hour. Required parts 
will cost approximately $1,098 if only components are replaced, or 
$7690 if the entire clutch assembly is replaced, per helicopter. Based 
on these figures, the total cost impact of the proposed AD on U.S. 
operators is estimated to be $4,527,600 to accomplish one inspection 
and replace components, or $19,030,000 to accomplish one inspection and 
replace the entire clutch assembly.

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 should 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 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 No. 97-SW-47-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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 a new airworthiness directive 
to read as follows:

AD 98-21-12  McDonnell Douglas Helicopter Systems: Amendment 39-
10820. Docket No. 97-SW-47-AD.

    Applicability: Model 369D, 369E, 369FF, 500N, AH-6, and MH-6 
helicopters, with overrunning clutch assembly, part number (P/N) 
369F5450-501, installed, certificated in any category.

    Note 1: This AD applies to each helicopter 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 helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (d) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect wear of other clutch components, excessive vibration 
which could lead to failure of the overrunning clutch, wear on the 
bearing carrier, and subsequent loss of power to the helicopter 
rotor drive system, accomplish the following:
    (a) Visually inspect the overrunning clutch retainer, P/N 
369F5460-1, carrier, P/N 369F5461-1, housing, P/N 369F5451-1, and 
pin, P/N MS16556-801, for clutch or carrier wear or pin damage in 
accordance with the Accomplishment Instructions in McDonnell Douglas 
Helicopter Systems Service Information Notice No. DN-190, EN-83, FN-
70, NN-011, dated July 25, 1997. For

[[Page 53802]]

helicopters with a clutch assembly having less than 100 hours time-
in-service (TIS), conduct the visual inspection before or upon 
reaching 100 hours TIS. For helicopters with a clutch assembly 
having 100 or more hours TIS, conduct the visual inspection within 
25 hours TIS.
    (b) Repeat the inspection required by paragraph (a) at intervals 
not to exceed 100 hours TIS.
    (c) If the inspections specified in paragraph (a) or (b) reveal 
wear or damage to components, replace those components with 
airworthy components prior to further flight.
    (d) 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, FAA. Operators shall submit their requests through an FAA 
Principal Maintenance Inspector, who may concur or comment and then 
send it to the Manager, Los Angeles Aircraft Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles Aircraft Certification Office.

    (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 helicopter to a location where 
the requirements of this AD can be accomplished.
    (f) The inspections shall be done in accordance with McDonnell 
Douglas Helicopter Systems Service Information Notice No. DN-190, 
EN-83, FN-70, NN-011, dated July 25, 1997. 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 Helicopter Systems, Field Service 
Department, 5000 E. McDowell Road, Mesa, Arizona, telephone (800) 
388-3378, fax (602) 891-6782. Copies may be inspected at the FAA, 
Office of the Regional Counsel, Southwest Region, 2601 Meacham 
Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (g) This amendment becomes effective on October 22, 1998.
    Issued in Fort Worth, Texas, on September 30, 1998. original 
signed by
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 98-26821 Filed 10-6-98; 8:45 am]
BILLING CODE 4910-13-U