[Federal Register Volume 64, Number 138 (Tuesday, July 20, 1999)]
[Rules and Regulations]
[Pages 38817-38820]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18367]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-40-AD; Amendment 39-11228; AD 99-13-09]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc (MDHI) Model 369D 
and E 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) 99-13-09 which was sent 
previously to all known U.S. owners and operators of MDHI Model 369D 
and E helicopters by individual letters. This AD requires, prior to 
further flight, inspecting and replacing, if necessary, a certain four-
bladed tail rotor fork (fork) assembly. This AD also requires a 
repetitive inspection of certain fork assemblies at intervals not to 
exceed 50 hours time-in-service (TIS) and removing and replacing, if 
necessary, each unairworthy fork assembly with an airworthy fork 
assembly before further flight. This amendment is prompted by reports 
from the manufacturer of the discovery of a discrepant part. The 
actions specified by this AD are intended to prevent failure of certain 
fork assemblies, which could cause loss of a tail rotor blade and 
subsequent loss of control of the helicopter.

DATES: Effective August 4, 1999, to all persons except those persons to 
whom it was made immediately effective by Priority Letter AD 99-13-09, 
issued on June 16, 1999, which contained the requirements of this 
amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before September 20, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-40-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: John L. Cecil, Aerospace Engineer, 
FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 
Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5228, 
fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On June 16, 1999, the FAA issued Priority 
Letter AD 99-13-09, applicable to MDHI Model 369D and E helicopters 
with fork assembly, part number (P/N) 369D21701-2 installed, which 
requires, prior to further flight, inspecting each fork assembly, P/N 
369D21701-2, for the presence of ridges on the arms and, if no ridges 
are present, conducting a dye-penetrant and visual inspection for 
cracks. If a crack is found, the fork assembly must be replaced with an 
airworthy fork assembly that has ridges. This AD also requires a 
repetitive visual inspection at intervals not to exceed 50 hours TIS of 
those fork assemblies without ridges that are currently installed but 
for which the initial visual and dye-penetrant inspection did not 
uncover a crack and removing and replacing, if necessary, each 
unairworthy fork assembly with an airworthy fork assembly before 
further flight. That action was prompted by reports from the 
manufacturer of the discovery of a discrepant part. During the 
manufacturing process, an unknown number of certain fork assemblies 
were incorrectly machined in critical areas after the shot-peening 
process. The two ridges on each of the arms of the fork assemblies were 
incorrectly machined off. This condition, if not corrected, could 
result in failure of certain fork assemblies, which could cause loss of 
a tail rotor blade and subsequent loss of control of the helicopter.
    Since the unsafe condition described is likely to exist or develop 
on other MDHI Model 369D and E helicopters of the same type design, the 
FAA issued Priority Letter AD 99-13-09 to prevent failure of the fork 
assembly which can result in loss of a tail rotor blade and subsequent 
loss of control of the helicopter. The AD requires, prior to further 
flight, inspecting and replacing, if necessary, the fork assembly, P/N 
369D21701-21, with an airworthy fork assembly. This AD also requires a 
repetitive inspection of P/N 369D21701-21 without ridges, at intervals 
not to exceed 50 hours TIS and removing and replacing, if necessary, 
each unairworthy fork assembly with an airworthy fork assembly before 
further flight. The actions are required to be accomplished in the area 
defined in Figure 1, Sheet 2 of 2 of this AD. The short compliance time 
involved is required because the previously described critical unsafe 
condition can adversely affect the structural integrity of the 
helicopter. Therefore, inspecting and replacing, if necessary, the fork 
assembly, P/N 369D21701-21, with an airworthy fork assembly is required 
prior to 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 June 16, 1999 to all known U.S. owners and operators of MDHI 
Model 369D and E 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 24 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 2 work hours per 
helicopter to perform the initial inspection and 1 work hour per 
helicopter for each repetitive inspection. Replacing a fork assembly, 
if necessary, will take approximately 5 work hours. The average labor 
rate is $60 per work hour. The manufacturer states that there will be 
no parts cost since the required parts are covered under the 
manufacturer's warranty. Based on these figures, the total cost impact 
of the AD on U.S. operators is estimated to be $20,880; assuming $2,880 
for the initial inspection of the entire fleet, $14,400 for 10 
repetitive inspections for the entire fleet, and $3,600 to replace 12 
fork assemblies.

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

[[Page 38818]]

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-40-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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 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.
    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.

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:

AD 99-13-09 MD Helicopters, Inc.: Amendment 39-11228. Docket No. 99-
SW-40-AD.

    Applicability: Model 369D and E helicopters, with four-bladed 
tail rotor fork (fork) assemblies, part number (P/N) 369D21701-21, 
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 as indicated, unless accomplished 
previously.
    To prevent failure of the fork assembly, P/N 369D21701-21, which 
can result in loss of a tail rotor blade and subsequent loss of 
control of the helicopter, accomplish the following:
    (a) Before further flight, inspect each fork assembly, P/N 
369D21701-21, for the presence of ridges on the arms. See Figure 1, 
sheets 1 and 2.

    Note 2: MD Helicopters, Inc., Service Bulletin SB369D-198, 
SB369E-092, dated May 10, 1999, pertains to the subject of this AD.

    (1) If ridges are found, no further action is required by this 
AD.
    (2) If no ridges are found, chemically remove paint from the 
machined areas, inspect the fork assembly for a crack using the dye-
penetrant procedure of MIL-STD-6866 or ASTM-E1417, and conduct a 
visual inspection using a 10X or higher magnifying glass. (See 
Figure 1, sheets 1 and 2.) Replace a cracked fork assembly with an 
airworthy fork assembly. A fork assembly without ridges, P/N 
369D21701-21, may not be installed.

    Note 3: The fork assembly is titanium, which requires dwell 
times for the dye-penetrant inspection that are appropriate for 
titanium.

    (b) Thereafter, at intervals not to exceed 50 hours time-in-
service (TIS), visually inspect each fork assembly without ridges, 
P/N 369D21701-21, for a crack using a 10X or higher magnifying 
glass. (See Figure 1, sheets 1 and 2.) If a crack is found, replace 
the cracked fork assembly with an airworthy fork assembly. A fork 
assembly without ridges, P/N 369D21701-21, may not be installed.
    (c) Replacing an unairworthy fork assembly with an airworthy 
fork assembly other than P/N 369D21701-21 without ridges constitutes 
terminating action for this AD.
    (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 4: 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.

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    (e) Special flight permits will not be issued.
    (f) This amendment becomes effective on August 4, 1999, to all 
persons except those persons to whom it was made immediately 
effective by Priority Letter AD 99-13-09, issued June 16, 1999, 
which contained the requirements of this amendment.
    Issued in Fort Worth, Texas, on July 13, 1999.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-18367 Filed 7-19-99; 8:45 am]
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