[Federal Register Volume 70, Number 27 (Thursday, February 10, 2005)]
[Proposed Rules]
[Pages 7063-7065]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-2608]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2004-SW-16-AD]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc. Model 600N 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes superseding an existing airworthiness 
directive (AD) for the MD Helicopters, Inc. (MDHI) Model 600N 
helicopters. That AD currently requires certain inspections of both 
upper tailboom attachments, nutplates, and angles for a crack or thread 
damage, and repairing or replacing any cracked or damaged part. Also, 
that AD requires replacing certain tailboom attachment bolts, adding a 
washer to each bolt, and modifying both upper access covers. This 
action would require installing six additional inspection holes in the 
aft fuselage skin panels and inspecting the upper and lower tailboom 
attachment fittings, the upper longerons, and the angles and nutplates 
for cracks. Also, the AD would provide a terminating action of 
modifying the fuselage aft section to strengthen the tailboom 
attachments and longerons. This proposal is prompted by an analysis 
that shows that certain tailboom attachments and longerons may develop 
cracks. The actions specified by the proposed AD are intended to 
prevent failure of a tailboom attachment, loss of the tailboom, and 
subsequent loss of control of the helicopter.

DATES: Comments must be received on or before April 11, 2005.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2004-SW-16-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 Office of the Regional Counsel between 
9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Fred Guerin, Aviation Safety 
Engineers, FAA, Los Angeles Aircraft Certification Office, Airframe 
Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone 
(562) 627-5232, 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 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. 2004-SW-16-AD.'' The postcard will be date 
stamped and returned to the commenter.

Discussion

    On November 28, 2001, the FAA issued Emergency AD 2001-24-51 for 
MDHI Model 600N helicopters and issued the final rule; request for 
comments on April 2, 2002 (Amendment 39-12706 (67 FR 17934, April 12, 
2002)). That AD requires implementing the procedures described in MD 
Helicopters, Inc. Service Bulletin SB600N-03, dated November 2, 2001 
(SB600N-03), for inspecting both upper tailboom attachments, nutplates, 
and angles for a crack or thread damage and repairing or replacing 
damaged parts. In addition, if one bolt is broken, the AD requires 
replacing all four bolts. Also, adding a washer to each bolt and 
modifying both upper access covers as well as a 25-hour time-in-service 
(TIS) repetitive borescope inspection of the tailboom attachments, 
nutplates, and angles is required. That action was prompted by the 
discovery of cracked bolts and attachments on several helicopters. The 
requirements of that AD are intended to prevent failure of a tailboom 
attachment, loss of the tailboom, and subsequent loss of control of the 
helicopter.
    Since issuing that AD, the FAA has reviewed an analysis by the 
manufacturer and has determined that the tailboom fittings, part number 
(P/N) 500N3422-BSC (BSC is interchangeable with basic) and -3, and the 
upper longerons, P/N 500N3120-3 and -4, will develop cracks due to the 
same design error as the current AD. Also, the FAA has reviewed MDHI 
Service Bulletin SB600N-039, dated December 9, 2003, which provides 
information pertaining to adding six inspection holes in the fuselage 
and certain inspections of the tailboom attachment fittings and upper 
longerons for cracks. Also, MDHI has issued Technical Bulletin TB 600N-
007, dated January 12, 2004, which provides information pertaining to 
modifying the fuselage aft section to strengthen tailboom attachment 
fittings and longerons.
    This previously described unsafe condition is likely to exist or 
develop on other helicopters of the same type design. Therefore, the 
proposed AD would supersede AD 2001-24-51 to require the following:
     Before further flight, drill an inspection hole at 
fuselage station L167 and R167 (L indicates Left and R indicates Right) 
on each side of the fuselage.
     Within 25 hours time-in-service (TIS):
     Drill two additional inspection holes on each side of the 
fuselage at L166, R166, L153, and R153.
     Visually inspect the lower attachment fittings and the 
upper longerons through inspection holes at L166, R166, L153 and R153, 
respectively.
     Thereafter, at specified intervals, remove the plug 
buttons from the inspection holes at L167, R167, L166,

[[Page 7064]]

and R166. Using a bright light, inspect the attachment fittings, 
angles, and nutplates for a crack. Through inspection holes L153 and 
R153, using a bright light and mirror or borescope, visually inspect 
the bottom surface of each longeron for a crack.
     Before further flight, replace any cracked attachment 
fitting, angle, nutplate, longeron, and any nutplate with thread damage 
with an appropriate airworthy part.
    This action proposes to require that operators modify the aft 
fuselage to strengthen the tailboom attachments and longeron within 4 
years, which would constitute terminating action for the requirements 
of the AD.
    The FAA estimates that this proposed AD would affect 39 helicopters 
of U.S. registry. The proposed actions would take about 322 work hours 
to modify and inspect the fuselage aft section per helicopter at an 
average labor rate of $65 per work hour. Required parts would cost 
approximately $14,960 per helicopter. Based on these figures, we 
estimate the total cost impact of the proposed AD on U.S. operators to 
be $1,399,710.

Regulatory Findings

    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 
economic 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.

Authority for this Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

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 39-12706 (67 FR 
17934) and by adding a new airworthiness directive (AD), to read as 
follows:

MD Helicopters, Inc.: Docket No. 2004-SW-16-AD. Supersedes AD 2001-
24-51, Amendment 39-12706, Docket No. 2001-SW-57-AD.

    Applicability: Model 600N, serial numbers with a prefix of 
``RN'' 003 through 066 and 068, that have not been modified by 
following the Accomplishment Instructions of MDHI Technical Bulletin 
TB600N-007, dated January 12, 2004, certificated in any category.
    Compliance: Required as indicated.
    To prevent failure of a tailboom attachment, loss of the 
tailboom, and subsequent loss of control of the helicopter, 
accomplish the following:
    (a) Before further flight, unless accomplished previously, drill 
an inspection hole at fuselage station L167 and R167 (L indicates 
Left and R indicates Right) on each side of the fuselage by 
following the Accomplishment Instructions, paragraph 2.B.(6) of MD 
Helicopters, Inc. (MDHI) Service Bulletin SB600N-036, dated November 
2, 2001.
    (b) Within 25 hours time-in-service (TIS), unless accomplished 
previously:
    (1) Drill two additional inspection holes (L166 and L153 on the 
left side and R166 and R153 on the right side) on each side of the 
fuselage as shown for the left side of the fuselage in Figure 1 of 
MDHI SB600N-039, dated December 9, 2003 (SB-039), by following the 
Accomplishment Instruction paragraphs of SB-039 as follows:
    (i) Paragraphs 2.A.(1)(a), (b), and (d) for inspection holes at 
L166 and R166;
    (ii) Paragraphs 2.A.(2)(a), (b), and (d) for inspection holes at 
L153 and R153; and
    (2) Visually inspect for a crack by following the Accomplishment 
Instruction paragraphs of SB-039 at the following locations, except 
you are not required to contact MDHI.
    (i) The lower left and right attachment fittings through 
inspection holes at L166 and R166, paragraph 2.A.(1)(c).
    (ii) The upper left and right longerons through inspection holes 
at L153 and R153, paragraph 2.A.(2)(c).

    Note: The reference in Figure 1 of SB-039 to inspection hole at 
L167 mistakenly states that it was ``Added by SB900-036.'' 
Inspection holes at L167 and R167 were originally specified by 
SB600N-036.

    (c) Thereafter, at the specified intervals, remove the plug 
buttons from the inspection holes, and using a bright light, inspect 
the upper left and upper right attachment fittings, angles, and 
nutplates for a crack by following the Accomplishment Instruction 
paragraphs of SB-039, as follows, except you are not required to 
contact MDHI.
    (1) At intervals not to exceed 25 hours TIS, for inspection 
holes at L167 and R167, inspect the upper left and upper right 
attachment fittings, angles, and nutplates by following paragraphs 
2.B.(2) through 2.B.(4).
    (2) At intervals not to exceed 100 hours TIS, for inspection 
holes at L166 and R166, inspect the lower left and lower right 
attachment fittings, angles, and nutplates by following paragraphs 
2.B.(2) through 2.B.(4).
    (3) At intervals not to exceed 1200 hours TIS, for inspection 
holes L153 and R153 using a mirror or borescope, inspect the bottom 
surface of each longeron by following paragraphs 2.C.(2) and 
2.C.(3).
    (d) Before further flight, replace any cracked attachment 
fitting, angle, nutplate, longeron, and any nutplate with thread 
damage with an appropriate airworthy part.
    (e) On or before 4 years from the effective date of this AD, 
modify the aft fuselage to strengthen the tailboom attachments and 
the longerons by following the Accomplishment Instructions of MDHI 
Technical Bulletin TB600N-007, dated January 12, 2004 (TB-007). 
Modifying the aft fuselage by following TB-007 constitutes 
terminating action for the requirements of this AD.
    (f) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Contact the Los Angeles Aircraft Certification Office (LAACO), FAA, 
for information about previously approved alternative methods of 
compliance.


[[Page 7065]]


    Issued in Fort Worth, Texas, on February 2, 2005.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 05-2608 Filed 2-9-05; 8:45 am]
BILLING CODE 4910-13-P