Airworthiness Directives; Hiller Aircraft Corporation Model UH- 12A, UH-12B, UH-12C, UH-12D, and UH-12E Helicopters

[Federal Register Volume 60, Number 110 (Thursday, June 8, 1995)]
[Rules and Regulations]
[Pages 30184-30186]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-13410]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-SW-13-AD; Amendment 39-9252; AD 95-12-02]


Airworthiness Directives; Hiller Aircraft Corporation Model UH-
12A, UH-12B, UH-12C, UH-12D, and UH-12E Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to Hiller Aircraft Corporation (Hiller) Model UH-12A, UH-
12B, UH- [[Page 30185]] 12C, UH-12D, and UH-12E helicopters. This 
action requires a dye-penetrant inspection of the head of the main 
rotor outboard tension-torsion (T-T) bar pin for cracks; a visual 
inspection of the outboard T-T bar pin for proper alignment, and an 
adjustment, if necessary; and, installation of shims at the inboard end 
of the drag strut. This amendment is prompted by two accidents 
involving failure of the outboard T-T bar pin on Hiller UH-12E 
helicopters. The actions specified by this AD are intended to prevent 
cracks in the head area of the outboard T-T bar pin, which could result 
in loss of in-plane stability of the main rotor blade and subsequent 
loss of control of the helicopter.

DATES: Effective on June 23, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 23, 1995.
    Comments for inclusion in the Rules Docket must be received on or 
before August 7, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 95-SW-13-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137.
    The service information referenced in this AD may be obtained from 
Hiller Aircraft Corporation, 7980 Enterprise Drive, Newark, California 
94560-3497. This information may be examined at the FAA, Office of the 
Assistant Chief Counsel, 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: Mr. Charles Matheis, Aerospace 
Engineer, FAA, Los Angeles Aircraft Certification Office, 3960 
Paramount Blvd., Lakewood, California 90712-4137, telephone (310) 627-
5235, fax (310) 627-5210.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is 
applicable to Hiller Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E 
helicopters. This AD is prompted by two accidents, both involving Model 
UH-12E helicopters, in which failure of the outboard T-T bar pin, part 
number (P/N) 51452, was subsequently determined to be the cause of the 
accidents. The Hiller Model UH-12E helicopter main rotor system design 
is similar to the main rotor system design of the Hiller Model UH-12A, 
UH-12B, UH-12C, and UH-12D helicopters. The outboard T-T bar pin 
extends from the main rotor blade root fork and serves as an attachment 
point for the inboard end of the main rotor blade drag strut. The drag 
strut fixes the in-plane stability of the main rotor blade and 
transfers the drag forces applied by the main rotor blade to the main 
rotor hub.
    The National Transportation Safety Board (NTSB) issued Safety 
Recommendation A-94-189, dated November 30, 1994, which states that 
both failures resulted from fatigue cracks that originated from the 
bolt through-hole of an outboard T-T bar pin. The NTSB investigation 
revealed that improper alignment and excessive play between the 
outboard T-T bar pin and the inboard end of the drag strut can 
introduce large operating stresses in the head of the outboard T-T bar 
pin. A fracture of the outboard T-T bar pin allows the main rotor blade 
to rotate freely about the blade hub, resulting in a loss of in-plane 
stability. Any cracks in the head of the outboard T-T bar pin create an 
unsafe condition. Due to the criticality of the outboard T-T bar pin in 
maintaining main rotor blade stability, and the relatively short 
compliance time, this AD is being issued immediately to correct an 
unsafe condition. The actions required by this AD include an inspection 
for cracks in the head of the outboard T-T bar pin using a dye-
penetrant inspection method; an inspection to ensure the proper 
alignment of the outboard T-T bar pin; and, the installation of shims 
between the inboard end of the drag strut and the outboard T-T bar pin. 
The FAA has determined that correcting any misalignment can reduce 
large stresses, and can therefore reduce the likelihood of cracking the 
head of the outboard T-T bar pin. That condition, if not corrected, 
could result in loss of in-plane stability of the main rotor blade and 
subsequent loss of control of the helicopter.
    The FAA has reviewed Hiller Aviation Service Bulletin (SB) No. 51-
9, dated April 8, 1983, which describes procedures for the installation 
of shims between the inboard end of the drag strut and the outboard T-T 
bar pin; and Hiller Aviation Service Letter (SL) 51-2, dated March 31, 
1978, which describes procedures for an inspection to ensure proper 
alignment of the outboard T-T bar pin, and an inspection of the head of 
the outboard T-T bar pin for cracks using a dye-penetrant inspection 
method. The FAA has determined that the compliance times prescribed in 
those service documents are not adequate to ensure safety of flight, 
and is revising those compliance times in this AD.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Hiller Model UH-12A, UH-12B, UH-12C, UH-12D, 
and UH-12E helicopters of the same type design, this AD is being issued 
to prevent cracks in the head area of the outboard T-T bar pin. This AD 
requires, within 25 hours time-in-service (TIS) or at the next 100 
hours TIS inspection, whichever occurs first, and thereafter at 
intervals not to exceed 100 hours TIS: (1) an inspection of the 
alignment of the outboard T-T bar pin and an adjustment, if necessary; 
and (2) an inspection for cracks in the head of the outboard T-T bar 
pin using a dye penetrant inspection method. Additionally, this AD 
requires, within 25 hours TIS or at the next 100 hours TIS inspection, 
whichever occurs first, the installation of shims between the inboard 
end of the drag strut and the outboard T-T bar pin. The procedures to 
perform these actions are required to be accomplished in accordance 
with the service bulletin and service letter described previously, but 
in accordance with the compliance times stated in this AD.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

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, 
[[Page 30186]] 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. 95-SW-13-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, 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR section 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

95-12-02 Hiller Aircraft Corporation: Amendment 39-9252. Docket No. 
95-SW-13-AD.

    Applicability: Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E 
helicopters, certificated in any category.

    Note 1: This AD applies to each helicopter identified in the 
preceding applicability provision, regardless of whether it has been 
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 use the authority 
provided in paragraph (e) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent cracks in the head area of the main rotor outboard 
tension-torsion (T-T) bar pin, which could result in loss of in-
plane stability of the main rotor blade and subsequent loss of 
control of the helicopter, accomplish the following:
    (a) Within 25 hours time-in-service (TIS) after the effective 
date of this AD, or at the next 100 hours TIS inspection, whichever 
occurs first, and thereafter at intervals not to exceed 100 hours 
TIS, inspect the alignment of the outboard T-T bar pin, part number 
(P/N) 51452, and adjust the alignment, if necessary, in accordance 
with Hiller Aviation Service Letter (SL) 51-2, dated March 31, 1978.
    (b) Inspect the head of the outboard T-T bar pin for cracks 
using a dye-penetrant inspection method.
    (c) Report the results of the dye-penetrant inspections required 
by paragraph (b) of this AD within 7 days following each inspection 
to the Manager, Los Angeles Aircraft Certification Office, 
Attention: Charles Matheis, ANM-120L, 3960 Paramount Blvd., 
Lakewood, California 90712-4137. Include the helicopter model 
number, serial number, and total TIS of the outboard T-T bar pin in 
the report. Reporting requirements have been approved by the Office 
of Management and Budget and assigned OMB control number 2120-0056.
    (d) Within 25 hours TIS after the effective date of this AD, or 
at the next 100 hours TIS inspection, whichever occurs first, 
install shims between the inboard end of the drag strut and the 
outboard T-T bar pin in accordance with the Accomplishment 
Instructions of Hiller Aviation Service Bulletin No. 51-9, dated 
April 8, 1983.
    (e) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used when approved by the Manager, Los Angles 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 may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR sections 21.197 and 21.199) to operate the helicopter to a 
location where the requirements of this AD can be accomplished.
    (g) The inspections, modifications, and adjustments, if 
necessary, shall be done in accordance with Hiller Aviation Service 
Bulletin No. 51-9, dated April 8, 1983, and Hiller Aviation Service 
Letter 51-2, dated March 31, 1978. 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 
Hiller Aircraft Corporation, 7980 Enterprise Drive, Newark, 
California 94560-3497. Copies may be inspected at the FAA, Office of 
the Assistant Chief Counsel, 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 June 23, 1995.

    Issued in Fort Worth, Texas, on May 25, 1995.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-13410 Filed 6-7-95; 8:45 am]
BILLING CODE 4910-13-P

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