Airworthiness Directives; Bell Helicopter Textron, Inc. Manufactured Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, UH-1P, TH- 1F and TH-1L Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-SW-08-AD; Amendment 39-9058; AD 94-22-09]

Airworthiness Directives; Bell Helicopter Textron, Inc.--

Manufactured Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, UH-1P, TH-

1F and TH-1L Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to Bell Helicopter Textron, Inc. restricted category

military Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and TH-1L

helicopters, that currently requires an inspection before the first

flight of each day of certain tail rotor drive shafts and the tail

rotor drive shaft hanger bearings (bearings) for grease leakage,

security, overheat conditions, binding, or roughness until the bearings

are replaced. This amendment requires the same inspection of the

bearings, but also requires replacement of the affected bearings within

the next 100 hours time-in-service and extends the requirements of this

AD to the Model UH-1P and TH-1F helicopters that were recently type

certificated. This amendment is prompted by an accident involving a

bearing failure, and by the certification of two additional affected

helicopter models. The actions specified by this AD are intended to

prevent failure of the bearing, failure of the tail rotor drive shaft,

and subsequent loss of control of the helicopter.

DATES: Effective November 22, 1994.

Comments for inclusion in the Rules Docket must be received on or

before January 6, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Office of the Assistant Chief Counsel, Attention:

Rules Docket No. 93-SW-08-AD, 2601 Meacham Boulevard, Room 663, Fort

Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Mr. Uday Garadi, Aerospace Engineer,

Rotorcraft Certification Office, FAA, Rotorcraft Directorate, 2601

Meacham Boulevard, Fort Worth, Texas 76137, telephone (817) 222-5157,

fax (817) 222-5959.

SUPPLEMENTARY INFORMATION: On February 5, 1992, the FAA issued Priority

Letter (PL) AD 92-03-14, applicable to Bell Helicopter Textron, Inc.

(BHTI)-manufactured Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and

TH-1L helicopters, to require an inspection before the first flight of

each day of certain tail rotor

(T/R) drive shafts and T/R drive shaft hanger bearings (bearings) for

grease leakage, security, overheat conditions, binding, or roughness

until the affected bearings are replaced. That action was prompted by

an accident involving a BHTI Model 412 helicopter that experienced a

bearing failure. Inspections performed as part of the accident

investigation found metal particles from the manufacturing process in

the bearings. Contaminated bearings can seize and stop rotating,

causing the spline coupling shaft to rotate inside the bearing and

overheat. That condition, if not corrected, could result in failure of

the bearing, failure of the T/R drive shaft, and subsequent loss of

control of the helicopter.

Since the issuance of that AD, the FAA has determined that the

affected bearings need to be replaced within the next 100 hours time-

in-service in lieu of continued inspections before the first flight of

each day as required by the PL AD. In addition, Type Certificate No.

H12NM was issued March 30, 1993, to Western International Aviation,

Inc. for Model UH-1F, UH-1P, and TH-1F helicopters that use the same

bearings. Therefore, this AD should be applicable to these model

helicopters. Also, some editorial changes were made to the AD.

Since an unsafe condition has been identified that is likely to

exist or develop on other helicopters of the same type design, this AD

supersedes PL AD 92-03-14 to require the same inspection of the

affected bearings, but also to require replacement of the affected

bearings within the next 100 hours time-in-service. Due to the critical

need to ensure the integrity of the bearings that maintain control of

the T/R drive shaft through which power is provided to the T/R system,

to comply with the requirements of this AD before the first flight of

each day, and to start the required inspections on the additionally-

affected model helicopters, this rule must be issued immediately to

correct an unsafe condition in the affected helicopters.

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, 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 Number 93-SW-08-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. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive

(AD), Amendment 39-9058, to read as follows:

AD 94-22-09 California Department of Forestry; Garlick Helicopters;

Hawkins and Powers Aviation, Inc.; Hercules; International

Helicopters, Inc.; Offshore Construction; Oregon Helicopters; Pilot

Personnel International, Inc.; Smith Helicopters; Southern Aero

Corporation; Southwest Florida Aviation; West Coast Fabrications;

and Western International Aviation Inc.: Amendment 39-9058. Docket

Number 93-SW-08-AD. Supersedes Priority Letter AD 92-03-14, Docket

No. 91-ASW-32.

Applicability: Bell Helicopter Textron, Inc.--manufactured Model

UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, UH-1P, TH-1F, and TH-1L

helicopters, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously. To prevent failure of a tail rotor (T/R) drive shaft

hanger bearing (bearing), failure of the T/R drive shaft, and

subsequent loss of control of the helicopter, accomplish the

following:

(a) Before further flight, after the effective date of this AD,

determine the serial number (S/N) etched on the seal area of the

bearing, part number (P/N) 204-040-623-005. If the bearing has a S/N

with a prefix of T or N, accomplish the inspection specified in

paragraph (b) until the affected bearing is replaced in accordance

with paragraph (d) of this AD.

Note: Bearings with a S/N prefix of NC are not required to

comply with this AD.

(b) Before the first flight of each day, until the affected

bearings are replaced in accordance with paragraph (d) of this AD,

accomplish the following inspections of the T/R drive shaft and

bearings:

(1) Visually inspect the bearings for grease leakage that

continues for more than 10 hours time-in-service after installation

of a zero-time bearing.

(2) Visually inspect the T/R drive shaft and the bearings and

housing for security and damage.

(3) Visually inspect the bearings for an overheat condition and

inspect overheat indicator stripes for discoloration.

(4) Rotate the T/R drive shaft by hand while feeling the bearing

housing for bearing binding or roughness.

(c) Before further flight, replace any bearings that exhibit

signs of continued grease leakage, overheating, binding, roughness,

or are otherwise unairworthy, and secure any insecure bearings and

housings in accordance with the applicable maintenance, repair, and

overhaul manuals.

(d) Within the next 100 hours time-in-service after the

effective date of this AD, remove from further service any bearing,

P/N 204-040-623-005, that has a S/N with a prefix of T or N, and

replace with a bearing, P/N 204-040-623-005, that has a S/N without a

prefix of T or N. Remove and replace the bearings in accordance with

the procedures in the applicable Bell Helicopter Textron, Inc.

maintenance, repair and overhaul manuals.

(e) Installation of bearings containing a prefix other than T or

N constitutes terminating action for the requirements of this AD.

(f) 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, Rotorcraft Certification Office,

FAA, Rotorcraft Directorate. Operators shall submit their requests

through an FAA Principal Maintenance Inspector, who may concur or

comment and then send it to the Manager, Rotorcraft Certification

Office.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Rotorcraft Certification Office.

(g) Special flight permits may be issued in accordance with

sections 21.197 and 21.199 of the Federal Aviation Regulations (14

CFR 21.197 and 21.199) to operate the helicopter to a location where

the requirements of this AD can be accomplished.

(h) This amendment becomes effective on November 22, 1994.

Issued in Fort Worth, Texas, on October 24, 1994.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 94-26880 Filed 11-4-94; 8:45 am]

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