Airworthiness Directives; McDonnell Douglas Helicopter Systems Model MD-900 Helicopters

[Federal Register Volume 62, Number 191 (Thursday, October 2, 1997)]
[Rules and Regulations]
[Pages 51593-51594]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-25970]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-SW-30-AD; Amendment 39-10149; AD 97-20-12]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Helicopter Systems 
Model MD-900 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to McDonnell Douglas Helicopter Systems (MDHS) Model MD-900 
helicopters, that requires removing certain serial-numbered main rotor 
swashplate bearings (bearings) and replacing them with airworthy 
bearings. This amendment is prompted by reports that inspections of 
several helicopters revealed that the outer bearing race had been 
rotating relative to the swashplate assembly, which was evidenced by 
wear marks in the rotating swashplate. The actions specified by this AD 
are intended to prevent possible heat accumulation and resulting damage 
to the bearing caused by the bearing races rotating relative to the 
bearing seat, which could result in degraded helicopter response to 
pilot control input and possible loss of control of the helicopter.

EFFECTIVE DATE: November 6, 1997.

FOR FURTHER INFORMATION CONTACT: Mr. Greg DiLibero, Aerospace Engineer, 
FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Blvd., 
Lakewood, California 90712, telephone (310) 627-5231, fax (310) 627-
5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to MDHS Model MD-900 helicopters was 
published in the Federal Register on January 29, 1997 (62 FR 4217). 
That action proposed to require, before further flight, inspecting the 
bearing, part number (P/N) 900C3010100-101, to determine if a bearing 
having serial number (S/N) 059150-E0019, S/N 059150-E0020, S/N 059150-
E0021, S/N 059150-E0022, S/N 059150-E0023, S/N 059150-E0024, S/N 
059150-E0025, S/N 059150-E0026, S/N 059150-E0027, S/N 059150-E0028, S/N 
059150-E0029, or S/N 059150-E0030 is installed; and, if installed, 
removing and replacing that bearing with an airworthy bearing.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposal or the FAA's determination of the cost to the public. The FAA 
has determined that air safety and the public interest require the 
adoption of the rule as proposed, with two changes. The FAA has 
determined that special flight permits may be issued to operate the 
helicopter to a location where the requirements of this AD can be 
accomplished. This is now stated in paragraph (i) of the AD. Also, the 
FAA has determined that this AD should only apply to the Model MD-900 
helicopters, not the Model MD-900 ``series'' helicopters. Therefore, 
the word ``series'' is removed from the applicability paragraph of this 
AD. The FAA has determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.
    The FAA estimates that 20 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 1.5 work hours per 
helicopter to determine the bearing's S/N, 12 work hours per helicopter 
to remove and replace a bearing, and that the average labor rate is $60 
per work hour. Replacement bearings would cost $8,765 per helicopter, 
however, replacement bearings are covered by a manufacturer's warranty. 
Based on these figures, the total cost impact of the AD on U.S. 
operators is estimated to be $5,400, assuming five helicopters will 
require removal and replacement of the bearing.
    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

[[Page 51594]]

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.
    For the reasons discussed above, I certify that this 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) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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, 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:

97-20-12  McDonnell Douglas Helicopter Systems: Amendment 39-10149. 
Docket No. 96-SW-30-AD.

    Applicability: Model MD-900 helicopters, 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 (h) 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 before further flight, unless accomplished 
previously.
    To prevent possible heat accumulation and resulting damage to 
the main rotor swashplate bearing (bearing) caused by the bearing 
races rotating relative to the bearing seat, which could result in 
degraded helicopter response to pilot control input and possible 
loss of control of the helicopter, accomplish the following:
    (a) Disconnect the lower end of the main rotor pitch links. 
Disconnecting the drive link may make the inspection easier.
    (b) Cut the safety wire and remove the inner and outer labyrinth 
seals, part number (P/N) 900C2010194-101 and P/N 900C201190-101, 
respectively, and the inner and outer bearing retaining rings.
    (c) Inspect the bearing, part number (P/N) 900C3010100-101, to 
determine if it has one of the following serial numbers (S/N): S/N 
059150-E0019, S/N 059150-E0020, S/N 059150-E0021, S/N 059150-E0022, 
S/N 059150-E0023, S/N 059150-E0024, S/N 059150-E0025, S/N 059150-
E0026, S/N 059150-E0027, S/N 059150-E0028, S/N 059150-E0029, or S/N 
059150-E0030.

    Note 2: S/N's similar to those above were produced without the 
character ``E'' in the number. This AD is only concerned with those 
that contain the character ``E''.

    (d) Enter into the helicopter Log Book the bearing S/N.
    (e) If a bearing having one of the S/N's stated in paragraph (c) 
of this AD is installed on the helicopter, remove the bearing and 
replace it with an airworthy bearing prior to further flight.
    (f) Prior to the installation of a swashplate assembly, inspect 
the bearing in accordance with the requirements of this AD.
    (g) Report the results of all inspections required by this AD 
within 72 hours to the Manager, Los Angeles Aircraft Certification 
Office, 3960 Paramount Blvd., Lakewood, California 90712. Reporting 
requirements have been approved by the Office of Management and 
Budget and assigned OMB control number 2120-0056.
    (h) 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 3: 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.

    (i) 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.
    (j) This amendment becomes effective on November 6, 1997.

    Issued in Fort Worth, Texas, on September 24, 1997.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 97-25970 Filed 10-1-97; 8:45 am]
BILLING CODE 4910-13-U

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