[Federal Register Volume 67, Number 238 (Wednesday, December 11, 2002)]
[Rules and Regulations]
[Pages 76109-76111]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-31176]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-SW-50-AD; Amendment 39-12975; AD 2002-22-51]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc. Model MD900 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) 2002-22-51, which was sent 
previously to all known U.S. owners and operators of MD Helicopters, 
Inc. (MDHI) Model MD900 helicopters by individual letters. This AD 
requires, before further flight, certain procedures and inspections of 
the main rotor support static mast (mast) and the mast threads for any 
crack or pitting. If any crack or pitting is found, this AD requires 
removing the mast from service. The actions specified by this AD are 
intended to detect any crack or pitting in the mast that could result 
in failure of the mast, separation of the main rotor, and subsequent 
loss of control of the helicopter.

DATES: Effective December 26, 2002, to all persons except those persons 
to whom it was made immediately effective by Emergency AD 2002-22-51, 
issued on October 23, 2002, which

[[Page 76110]]

contained the requirements of this amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before February 10, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2002-SW-50-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137. You may also send comments electronically 
to the Rules Docket at the following address: [email protected].

FOR FURTHER INFORMATION CONTACT: Jon Mowery, Aviation Safety Engineer, 
FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 
Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5322, 
fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On October 23, 2002, the FAA issued 
Emergency AD 2002-22-51 for the specified MDHI model helicopters, which 
requires, before further flight, removing the main rotor drive shaft to 
inspect the mast, removing the main rotor hub assembly to inspect the 
mast threads, and if a flaw is found in the mast threads, magnetic 
particle inspecting the mast threads for any crack or pitting. If any 
crack or pitting is found, the AD requires removing the mast from 
service. The cause of the cracking is under investigation, but 
preliminary analysis shows that lack of torque in the 12 bolts on the 
main rotor hub retention nut (nut) results in loss of preload in the 
mast. Without preload, the mast will incur alternating stresses that 
can lead to crack initiation. In the four reported cases, cracks were 
found in the mast less than 1 inch from the top. In at least one case, 
pitting was also found in this area. All of these cracks penetrated 
through the wall thickness. This condition, if not detected, can result 
in failure of the mast, separation of the main rotor, and subsequent 
loss of control of the helicopter.
    The FAA has reviewed MDHI Service Bulletin No. SB900-089R1, dated 
October 22, 2002, which describes procedures for checking the torque in 
the 12 bolts of the nut, inspecting the mast for a crack, and removing 
the mast from service if necessary.
    Since the unsafe condition described is likely to exist or develop 
on other specified helicopters of the same type design, the FAA issued 
Emergency AD 2002-22-51 to detect any crack or pitting that could 
result in failure of the mast, separation of the main rotor, and 
subsequent loss of control of the helicopter. The AD requires, before 
further flight, for MDHI Model MD900 helicopters, serial numbers 900-
00008 through 900-00110, with mast, part number 900F2401021-101, 
removing the main rotor drive shaft and inspecting the mast for any 
crack or pitting. The AD also requires removing the main rotor hub 
assembly and inspecting the mast threads for a crack. If a flaw is 
found in the thread root area and you cannot determine if it is a 
crack, the AD also requires a magnetic particle inspection (wet 
fluorescent) for a crack. If any crack or pitting is found, the AD 
requires removing the mast from service.
    The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
structural integrity of the helicopter. Therefore, conducting the 
specified inspections of the mast and mast threads for any crack or 
pitting are required, and removing the mast from service if any crack 
or pitting is found in any of the inspections is required before 
further flight, and this AD must be issued immediately.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual letters 
issued on October 23, 2002, to all known U.S. owners and operators of 
MDHI Model MD900 helicopters. These conditions still exist, and the AD 
is hereby published in the Federal Register as an amendment to 14 CFR 
39.13 to make it effective to all persons.
    The FAA estimates that this AD will affect 32 helicopters of U.S. 
registry, that it will take approximately 6 work hours to inspect and 8 
work hours to replace a mast, and that the average labor rate is $60 
per work hour. Required parts will cost approximately $45,000 per 
helicopter to replace a mast. Based on these figures, the total cost 
impact of the AD on U.S. operators is estimated to be $193,440, 
assuming that the inspections are performed on each helicopter and that 
the mast is replaced on 4 helicopters.

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 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 mailed 
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. 2002-SW-50-AD.'' The postcard will be date 
stamped and returned to the commenter.
    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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, Safety.

[[Page 76111]]

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:

2002-22-51 MD Helicopters, Inc.: Amendment 39-12975. Docket No. 
2002-SW-50-AD.

    Applicability: MD-900 helicopters, serial numbers 900-00008 
through 900-00110, with a main rotor support static mast (mast), 
part number 900F2401021-101, 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 
otherwise 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 request approval for an 
alternative method of compliance in accordance with paragraph (d) 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 before further flight, unless accomplished 
previously.
    To detect cracks and pitting in the mast that could result in 
failure of the mast, separation of the main rotor, and subsequent 
loss of control of the helicopter, accomplish the following:
    (a) Remove the main rotor drive shaft.

    Note 2: MD Helicopters, Inc. Service Bulletin No. SB900-089R1, 
dated October 22, 2002, pertains to the subject of this AD and has a 
Figure 1 depicting the inspection areas of the mast.

    (b) Remove 1 inch of primer from the top inside diameter of the 
mast. During paint removal, wipe the area clean. Do not scrub or 
flush the area. Do not allow paint stripper to run down the inside 
or outside surfaces of the mast below the work area or enter into 
the transmission. Inspect the top 1 inch of the inside diameter of 
the mast for a crack or pitting using a bright light and a 10x or 
higher magnifying glass. If you find any crack or pitting, remove 
the mast from service.
    (c) Remove the main rotor hub assembly. Clean the threads of the 
mast thoroughly with solvent. Inspect the mast threads for a crack 
using a bright light and a 20x or higher magnifying glass. Pay 
particular attention to the thread root area. If you see a flaw in 
the thread area and cannot determine if it is a crack, perform a 
magnetic particle inspection (wet fluorescent) per ASTM E 1444-01 
using an electromagnetic yoke or coil. If you find any crack or 
pitting, remove the mast from service.
    (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 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.

    (e) Special flight permits will not be issued.
    (f) This amendment becomes effective on December 26, 2002, to 
all persons except those persons to whom it was made immediately 
effective by Emergency AD 2002-22-51, issued October 23, 2002, which 
contained the requirements of this amendment.

    Issued in Fort Worth, Texas, on November 25, 2002.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 02-31176 Filed 12-10-02; 8:45 am]
BILLING CODE 4910-13-P