[Federal Register Volume 67, Number 185 (Tuesday, September 24, 2002)]
[Proposed Rules]
[Pages 59794-59797]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-24182]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-SW-40-AD]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc. Model 369D, 369E, 
369F, and 369FF Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes to revise an existing airworthiness 
directive (AD) for the specified MD Helicopters, Inc. (MDHI) 
helicopters. That AD currently requires identifying the part number (P/
N) of the bolts that attach the tail rotor gearbox to the tailboom and 
replacing any bolt of inadequate grip length with an airworthy bolt. 
That AD also requires adding an additional washer if more than four 
threads protrude from the nutplate. This action would contain the same 
requirements as the existing AD but would reduce the applicability to 
only certain tailboom serial numbers and parts modified in accordance 
with either Supplemental Type Certificate (STC) SH5055NM or SH4801NM. 
The action would also correct a typographical error and clarify that a 
slippage mark needs to be reapplied to each bolt regardless of the 
outcome of the required torque test. This proposal is prompted by the 
need to reduce the applicability and to correct and clarify other 
portions of the existing AD. The actions specified by the proposed AD 
are intended to prevent loss of a tail rotor gearbox due to bolts of 
inadequate grip length and subsequent loss of control of the 
helicopter.

DATES: Comments must be received by November 25, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2001-SW-40-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]. 
Comments may be inspected at the

[[Page 59795]]

Office of the Regional Counsel between 9 a.m. and 3 p.m., Monday 
through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: John Cecil, Aviation Safety Engineer, 
FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 
Paramount Blvd., Lakewood, California 90712-4137, telephone (562) 627-
5228, 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 should 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 document 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 mailed 
comments submitted in response to this proposal must submit a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. 2001-SW-40-AD.'' The postcard will be date 
stamped and returned to the commenter.

Discussion

    On June 18, 2002, the FAA issued AD 2002-13-05, Amendment 39-12793 
(67 FR 43227, June 27, 2002), for specified MDHI model helicopters with 
a tailboom modified according to either Aerometals STC SH5055NM or 
SH4801NM. These STC's were formerly owned by Yehnert Helicopters, Inc. 
That action was prompted by the discovery that the maintenance 
instructions supplied to installers of STC SH5055NM and SH4801NM 
incorrectly specified the tail rotor gearbox attaching bolt as S/B NAS 
1304-25, which has an inadequate grip length. That condition, if not 
corrected, could result in loss of a tail rotor gearbox and subsequent 
loss of control of the helicopter.
    Before its issuance, the FAA solicited comments to the proposed AD 
by a Notice of Proposed Rulemaking that was published in the Federal 
Register on December 27, 2001 (66 FR 66821). One commenter stated that 
the applicability of the AD should be limited to certain part-numbered 
tailbooms with serial number (S/N) 5001-5032 specified in the FAA-
approved Aerometals Service Bulletin. We did not agree with the 
commenter and, except for minor editorial changes, issued the AD as it 
had been proposed.
    Since the issuance of AD 2002-13-05, the FAA has determined that we 
inappropriately responded to the comment and that the commenter's 
concern was valid. We are now proposing to reduce the applicability of 
AD 2002-13-05 to include only certain tailboom serial numbers and parts 
that are modified in accordance with either STC SH5055NM or SH4801NM. 
We have also found that the P/N for washer, P/N AN960D416, was 
incorrect where referenced in Figure 1 and that clarification that a 
slippage mark needs to be reapplied to each bolt regardless of the 
outcome of the required torque test is necessary.
    The unsafe condition described previously is likely to exist or 
develop on other helicopters of these same type designs. Therefore, the 
actions required by AD 2002-13-05 will remain the same, but this 
proposed AD would reduce the applicability of AD 2002-13-05, correct 
the P/N for the washer, and clarify that a slippage mark must be 
reapplied to each bolt regardless of the outcome of the required torque 
test.
    The FAA estimates that this proposed AD would affect 500 
helicopters of U.S. registry. It would take approximately \1/2\ work 
hour per helicopter to determine whether a helicopter has been modified 
by either STC and 1 work hour to inspect and replace the bolts for each 
of approximately 40 helicopters modified by the STC's. The average 
labor rate is $60 per work hour. Required parts would cost 
approximately $40 per helicopter. Based on these figures, the total 
cost impact of the proposed AD on U.S. operators is estimated to be 
$19,000.
    The regulations proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    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 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 39-12793 (67 FR 
43227, June 27, 2002), and by adding a new airworthiness directive 
(AD), to read as follows:

MD Helicopters, Inc.: Docket No. 2001-SW-40-AD. Revises AD 2002-13-
05, Amendment 39-12793.

    Applicability: The following MD Helicopters, Inc. helicopter 
models, certificated in any category:

------------------------------------------------------------------------
                                                         Modified in
      Helicopter model                With             accordance with
------------------------------------------------------------------------
(1) 369D, 369E, 369F, 369FF.  Tailboom, serial      Aerometals
                               number (S/N) 5001-    Supplemental Type
                               5032.                 Certificate (STC)
                                                     SH5055NM.
(2) 369D and 369E...........  Tail Rotor Gearbox    Aerometals STC
                               Attach Bolts.         SH4801NM.
------------------------------------------------------------------------



[[Page 59796]]

    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 (c) 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 loss of the tail rotor gearbox due to attaching bolts 
of inadequate grip length and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) Within 25 hours time-in-service (TIS):
    (1) For each tail rotor gearbox attaching bolt (bolt):
    (i) Determine the part number (P/N).
    (ii) If the P/N cannot be determined or if the bolt is not P/N 
NAS1304-26, before further flight, replace the bolt with bolt, P/N 
NAS1304-26.
    (iii) Torque the bolt to 100-110 in-lbs and apply a slippage 
mark.
    (2) Remove the tailboom control rod and determine the number of 
bolt threads protruding from each nutplate on the internal surface 
of the aft tailboom frame casting, P/N 369D23503, as shown in Figure 
1 of this AD. At least one thread must protrude. If more than four 
threads protrude, add an additional washer, P/N AN960D416, under the 
bolt head. Torque the bolt to 100-110 in-lbs, and reapply a slippage 
mark. See Figure 1:
BILLING CODE 4910-13-P
[GRAPHIC] [TIFF OMITTED] TP24SE02.017

BILLING CODE 4910-13-C

[[Page 59797]]

    (b) Between 2 and 10 hours TIS after accomplishing the 
requirements of paragraph (a) of this AD, inspect the torque on each 
bolt by applying 100 in-lbs. If any bolt movement occurs, retorque 
the bolt to 100-110 in-lbs. Reapply a slippage mark to the bolt 
regardless of the outcome of the torque test. Reinspect the torque 
between 2 and 10 hours TIS thereafter until no bolt movement occurs.

    Note 2: Aerometals Service Bulletin SB-001, dated August 3, 
2000, pertains to the subject of this AD.

    (c) 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 (LAACO), FAA. Operators shall submit their requests through 
an FAA Principal Maintenance Inspector, who may concur or comment 
and then send it to the Manager, LAACO.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the LAACO.

    (d) Special flight permits will not be issued.

    Issued in Fort Worth, Texas, on September 13, 2002.
Eric D. Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 02-24182 Filed 9-23-02; 8:45 am]
BILLING CODE 4910-13-P