AD Amdt-39-11564

[Federal Register Volume 65, Number 31 (Tuesday, February 15, 2000)]
[Rules and Regulations]
[Pages 7428-7430]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-3222]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-71-AD; Amendment 39-11564; AD 99-25-08]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters Inc. Model 500N and 600N 
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 Emergency Priority Letter Airworthiness Directive (AD) 99-25-
08, which was sent previously to all known U.S. owners and operators of 
MD Helicopters Inc. (MDHI) Model 500N and 600N helicopters by 
individual letters. This AD requires, within the next 5 hours time-in-
service (TIS) or before further flight after December 31, 1999, 
whichever occurs first, inspecting the thruster control cable conduit 
cap (cap) for corrosion or a crack. This AD also requires, within the 
next 100 hours TIS or before further flight after February 19, 2000, 
whichever occurs first, inspecting the cap at a specified area of the 
forward and center thruster cables for corrosion or a crack. If an 
unacceptable crack is found, replacing the unairworthy thruster cable 
with an airworthy thruster cable is required. This amendment is 
prompted by the discovery of stress corrosion cracks on an MDHI Model 
500N helicopter. The actions specified by this AD are intended to 
prevent failure of the cap causing a fixed thruster condition and 
subsequent loss of normal anti-torque directional control of the 
helicopter.

DATES: Effective March 1, 2000, to all persons except those persons to 
whom it was made immediately effective by Emergency Priority Letter AD 
99-25-08, issued on November 26, 1999, which contained the requirements 
of this amendment.

[[Page 7429]]

    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 1, 2000.
    Comments for inclusion in the Rules Docket must be received on or 
before April 17, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-71-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.
    The applicable service information may be obtained from MD 
Helicopters Inc., Attn: Customer Support Division, 5000 E. McDowell 
Rd., Mail Stop M615-GO48, Mesa, Arizona 85215-9797, telephone 1-800-
388-3378 or 480-891-6342, fax 480-891-6782. This information may be 
examined at the FAA, Office of the Regional Counsel, Southwest Region, 
2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Fred A. Guerin, Aerospace Engineer, 
Airframe Branch, FAA, Los Angeles Aircraft Certification Office, 3960 
Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5232, 
fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On November 26, 1999, the FAA issued 
Emergency Priority Letter AD 99-25-08, applicable to MDHI Model 500N 
and 600N helicopters, which requires, within the next 5 hours time-in-
service (TIS) or before further flight after December 31, 1999, 
inspecting the cap for corrosion or a crack. The emergency priority 
letter AD also requires, within the next 100 hours TIS or before 
further flight after February 19, 2000, inspecting the cap for 
corrosion or a crack. If an unacceptable crack is found, replacing the 
unairworthy thruster cable with an airworthy thruster cable is 
required. That action was prompted by the discovery of stress corrosion 
cracks in the forward cap at the telescopic swivel end and the relieved 
area on an MDHI Model 500N helicopter. The forward thruster control 
cable in conjunction with the center thruster control cable 
simultaneously control the NOTAR directional control thruster and the 
left vertical stabilizer. This condition, if not corrected, could 
result in failure of the cap causing a fixed thruster condition and 
subsequent loss of normal anti-torque directional control of the 
helicopter.
    The FAA has reviewed MDHI Service Bulletin (SB) SB500N-021 SB600N-
028, dated November 19, 1999, and SB500N-020R1 SB600N-027R1, dated 
November 24, 1999, which describe procedures for inspecting the cap 
telescopic swivel end and the cap relieved area for corrosion or a 
crack and repairing or replacing the forward and center thruster 
control cables as specified.
    Since the unsafe condition described is likely to exist or develop 
on other MDHI Model 500N and 600N helicopters, which use the same 
forward thruster cable, the FAA issued Emergency Priority Letter AD 99-
25-08 to prevent failure of the cap causing a fixed thruster condition 
and subsequent loss of normal anti-torque directional control of the 
helicopter. The AD requires, within the next 5 hours TIS or before 
further flight after December 31, 1999, whichever occurs first, 
inspecting the cap at the telescopic swivel end of the forward and 
center thruster cables, part number (P/N) 500N7201-5, -7, -37, -45, or 
-51, for corrosion or a crack in accordance with SB500N-021 SB600N-028, 
dated November 19, 1999. This AD also requires, within the next 100 
hours TIS or before further flight after February 19, 2000, whichever 
occurs first, inspecting the cap at the relieved area of the forward 
and center thruster cables, part number (P/N) 500N7201-5, -7, -37, -45, 
or -51, for corrosion or a crack in accordance with SB500N-020R1 
SB600N-027R1, dated November 24, 1999. If an unacceptable crack is 
found, replacing the unairworthy thruster cable with an airworthy 
thruster cable is required. The actions must be accomplished in 
accordance with the SB's 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, inspecting the cap for corrosion or a crack is 
required before further flight and inspecting the cap at a specified 
area is required within 100 hours TIS or before further flight after 
February 19, 2000, whichever occurs first, 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 November 26, 1999, to all known U.S. owners and operators of 
MDHI Model 500N and 600N helicopters. These conditions still exist, and 
the AD is hereby published in the Federal Register as an amendment to 
section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to 
make it effective to all persons.
    The FAA estimates that 89 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 6 work hours per 
helicopter, per inspection, and 8 work hours to replace a thruster 
cable, if necessary. The average labor rate is $60 per work hour. 
Required parts will cost approximately $1,000 for each thruster cable 
replaced. Based on these figures, the total cost impact of the AD on 
U.S. operators is estimated to be $67,040, assuming 2 inspections per 
helicopter, per year, and replacement of 2 thruster cables.

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. 99-SW-71-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

[[Page 7430]]

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, 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:

AD99-25-08  MD Helicopters INC.: Amendment 39-11564. Docket No. 99-
SW-71-AD.

    Applicability: Model 500N helicopters, serial numbers (S/N) 001 
through 099 with a prefix of ``LN'', and Model 600N helicopters, S/N 
003 through 074 with a prefix of ``RN'', 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 (e) 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 failure of the thruster control cable conduit cap 
(cap) at the telescopic swivel end or relieved area and subsequent 
loss of normal anti-torque directional control of the helicopter, 
accomplish the following:
    (a) Within 5 hours time-in-service (TIS) or before further 
flight after December 31, 1999, whichever occurs first, inspect the 
forward and center thruster control cables, part number (P/N) 
500N7201-5, -7, -37, -45, or -51, installed in affected helicopters, 
for a crack, corrosion, or damage in the cap at the telescopic 
swivel end in accordance with the following paragraphs of the 
Accomplishment Instructions, Section 2, of MD Helicopters Inc. 
(MDHI) Service Bulletin SB500N-021 SB600N-028, dated November 19, 
1999 (SB 021/028).
    (1) Inspect the forward thruster control cables in accordance 
with paragraphs A.(1) through (5) of SB 021/028. Install safety wire 
in accordance with paragraph A.(7) of SB 021/028.
    (2) Inspect the center thruster control cable in accordance with 
paragraphs B.(1) through (4) and (6) of SB 021/028.
    (3) If an unacceptable crack or ball separation from the cap is 
found, remove and replace the unairworthy forward or center thruster 
control cable with an airworthy cable prior to further flight.
    (b) Within 100 hours TIS or before further flight after February 
19, 2000, whichever occurs first, inspect the forward and center 
thruster control cables, P/N 500N7201-5, -7, -37, -45, or -51, 
installed in affected helicopters in the cap relieved area for a 
crack, corrosion, or damage in accordance with the Accomplishment 
Instructions, Section 2, of MDHI SB SB500N-020R1 SB600N-027R1, dated 
November 24, 1999 (SB 020/027).
    (1) Inspect the forward thruster control cable for a crack or 
corrosion in accordance with paragraphs B.(1) through (5) and (7) of 
SB 020/027.
    (2) Inspect the center thruster control cable for a crack or 
corrosion in accordance with paragraphs C.(1) through (4), (6), and 
(for Model 600N only) (7) of SB 020/027.
    (3) If an unacceptable crack is found, remove and replace the 
unairworthy forward or center thruster control cable with an 
airworthy cable prior to further flight.
    (c) Repeat the inspections of paragraphs (a) and (b) of this AD 
at intervals not to exceed 100 hours TIS or 3 calendar months, 
whichever occurs first.
    (d) On or before December 1, 2000, replace the forward and 
center thruster control cables, part number (P/N) 500N7201-5, -7, -
37, and -45, and -51, with P/N 500N7201-55 and -57 on the MDHI Model 
500N or P/N 500N7201-55 and -59 on the MDHI Model 600N. 
Accomplishment of the requirements of this paragraph is terminating 
action for the requirements of this AD.
    (e) 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.

    (f) Special flight permits will not be issued.
    (g)(1) The inspections required within 5 hours time-in-service 
or before further flight after December 31, 1999, whichever occurs 
first, shall be done in accordance with the following paragraphs of 
the Accomplishment Instructions, Section 2, of MD Helicopters Inc. 
Service Bulletin SB500N-021 SB600N-028, dated November 19, 1999:
    (i) Paragraphs A.(1) through (5);
    (ii) Paragraph A.(7);
    (iii) Paragraphs B.(1) through (4) and (6).
    (2) The inspections required within 100 hours time-in-service 
shall be done in accordance with the following paragraphs of the 
Accomplishment Instructions, Section 2, of MDHI SB SB500N-020R1 
SB600N-027R1, dated November 24, 1999:
    (i) Paragraphs B.(1) through (5) and (7);
    (ii) Paragraphs C.(1) through (4), (6), and (for Model 600N 
only) (7).
    (3) 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 MD Helicopters Inc., Attn: 
Customer Support Division, 5000 E. McDowell Rd., Mail Stop M615-
GO48, Mesa, Arizona 85215-9797, telephone 1-800-388-3378 or 480-891-
6342, fax 480-891-6782. 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.
    (h) This amendment becomes effective on March 1, 2000, to all 
persons except those persons to whom it was made immediately 
effective by Emergency Priority Letter AD 99-25-08, issued November 
26, 1999, which contained the requirements of this amendment.

    Issued in Fort Worth, Texas, on February 7, 2000.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 00-3222 Filed 2-14-00; 8:45 am]
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