Airworthiness Directives; Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, and TH-55A Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-SW-17-AD]

Airworthiness Directives; Schweizer Aircraft Corporation and

Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, and TH-55A

Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to supersede an existing airworthiness

directive (AD), applicable to Schweizer Aircraft Corporation and Hughes

Helicopters, Inc. Model 269A, 269A-1, 269A-2, and 269B helicopters,

that currently requires initial and repetitive inspections of the main

rotor thrust bearing (bearing) for bearing rotational roughness,

corrosion, inadequate lubrication, physical damage, or excessive zinc

chromate paste or moisture. This action would require the same initial

and repetitive inspections required by the existing AD, but would

extend the retirement life for certain bearings, and would remove the

Model 269A-2 helicopter from, and add the Model TH-55A helicopters to

the applicability of this AD. This proposal is prompted by an FAA

analysis of service information issued by the

[[Page 30549]]

manufacturer that extends the retirement life for certain bearings. The

actions specified by the proposed AD are intended to prevent failure of

the bearing, loss of the main rotor, and subsequent loss of control of

the helicopter.

DATES: Comments must be received by August 16, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Rules Docket No. 94-SW-17-AD, 2601 Meacham Blvd., Room 663, Fort Worth,

Texas 76137. Comments may be inspected at this location between 9:00

a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be

obtained from Schweizer Aircraft Corporation, P.O. Box 147, Elmira, New

York 14902. This information may be examined at the FAA, Office of the

Assistant Chief Counsel, Room 663, 2601 Meacham Blvd., Fort Worth,

Texas.

FOR FURTHER INFORMATION CONTACT:

Mr. Ray O'Neill, Aerospace Engineer, Airframe and Propulsion Branch,

New York Aircraft Certification Office, FAA, New England Region, 10 5th

Street, Valley stream, New York 11581, telephone (516) 256-7505, fax

(516) 568-2716.

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,

specified above, will be considered before taking action on the

proposed rule. The proposals contained in this notice 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 comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket No. 94-SW-17-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request

to the FAA, Office of the Assistant Chief Counsel, Attention: Rules

Docket No. 94-SW-17-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas

76137

Discussion

On October 11, 1968, the FAA issued AD 68-21-05, Amendment 39-672

(33 FR 15543, October 19, 1968), to require, for Model 269A

helicopters, serial numbers (S/N) 0011 through 0979 (except Model TH-

55A helicopters), Model 269A-1 helicopters, S/N 0001 through 0041,

Model 269A-2 helicopter, S/N 0001, and Model 269B, S/N 0001 through

0370, an initial inspection at 25 hours time-in-service (TIS) and

thereafter, repetitive inspections at 150 hours TIS intervals of the

bearing, part number (P/N 269A5050-50 or P/N 269A5050-51, for bearing

corrosion, inadequate lubrication, physical damage, or evidence of

excessive zinc chromate paste or moisture; and, to establish a bearing

retirement life of 300 hours TIS. The AD was revised and issued on July

24, 1970 (35 FR 12532, August 6, 1970) to require, for bearings, P/N

269A5050-73, repetitive inspections at 600 hours TIS intervals for

bearing corrosion, rust, freedom of rotation, looseness, binding,

nicks, burrs, cracks, and inadequate lubrication; and to establish a

bearing retirement life of 1,800 hours TIS. These actions were prompted

by several reports of failures of the bearings in military-use

helicopters (Model TH-55a) that were equipped with the same bearings.

That condition, if not corrected, could result in failure of the main

rotor thrust bearing, loss of the main rotor, and subsequent loss of

control of the helicopter.

Since the issuance of that AD, Hughes Helicopters, Inc., issued a

report (Hughes Report JS-10-3, Revised May 4, 1979), which stated that

the retirement life for the bearing, P/N 269A5050-73, should be

extended from 1,800 hours TIS to 3,000 hours TIS. There have been no

reports of failures of that bearing since the issuance of AD 68-21-05.

In 1979, the FAA incorporated the 3,000 hours TIS retirement life into

Type Certificate Data Sheet 4H12, Revision 19, which governs Schweizer

Aircraft Corporation Model 269A, 269A-1, 269B, and former TH-55A

helicopters. Additionally, the Model 269A-2 Serial No. 0001) was

deleted from that Type Certificate Data Sheet. Therefore, the Model

269A-2 is removed from the applicability of this AD. Finally the Model

TH-55A helicopter was omitted from the applicability of the existing

AD, and has been added to the applicability of this AD.

Since an unsafe condition has been identified that is likely to

exist or develop another Schweizer Aircraft Corporation and Hughes

Helicopters, Inc. Model 269A, 269A-1, 269B, and TH-55A helicopters of

the same type design, the proposed AD would supersede AD 68-21-05 to

require the same initial and repetitive inspections required by the

existing AD, but extend the retirement life for bearings, P/N 269A5050-

73, from 1,800 hours TIS to 3,000 hours TIS.

The FAA estimates that 500 helicopters of U.S, registry would be

affected by this proposed AD, that it would take approximately 8 work

hours per helicopter to accomplish the proposed actions, and that the

average labor rate is $60 per work hour. Required parts would cost

approximately $1,890 per helicopter. Based on these figures, the total

cost impact of the proposed AD on U.S. operators is estimated to be

$1,185,000.

The regulations proposed herein would 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

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

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

regulatory 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.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

[[Page 30550]]

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 USC 106(g), 40113, and 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-1055 (35 FR

12532, August 6, 1970), and Amendment 39-672 (33 FR 15543, October 19,

1968), and by adding a new airworthiness directive (AD), to read as

follows:

Schweizer Aircraft Corporation and Hughes Helicopters, Inc.: Docket

No. 94-SW-17-AD. Supersedes AD 68-21-05, Amendment 39-1055 and

Amendment 39-672.

Applicability: Model 269A helicopters, serial numbers (S/N) 0011

through 1109, Model 269A-1 helicopters, S/N 0001 through 0041, Model

269B, S/N 0001 through 0444, and Model TH-55A, with main rotor

thrust bearing, part number (P/N) 269A5050-50, -51 or -73,

installed, certified 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 (g) 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 within 25 hours time-in-service (TIS) after

the effective date of this AD, unless accomplished previously.

To prevent failure of the main rotor thrust bearing, loss of the

main rotor, and subsequent loss of control of the helicopter,

accomplish the following:

(a) From available helicopter records, determine the TIS of the

appropriate main rotor thrust bearing (bearing), part number (P/N)

269A5050-50, 269A5050-51, or 269A5050-73.

(1) If the TIS on the bearing, P/N 269A5050-50 or -51, equals or

exceeds 300 hours TIS, replace the bearing before further flight.

(2) If the TIS on the hearing, P/N 269A5050-50 or -51, equals or

exceeds 275 hours TIS, retire the bearing from service within 25

hours TIS after the effective date of this AD.

(b) Inspect bearing, P/N 269A5050-50 or -51, for rotational

roughness, corrosion, inadequate lubrication, physical damage,

moisture or inadequate drainage due to build-up of zinc chromate

paste in accordance with Step II, paragraph b of Schweizer Service

Notice (SSN) No. N-59, dated October 9, 1968.

(1) If bearing rotational roughness, corrosion, inadequate

lubrication, physical damage, moisture or inadequate drainage due to

build-up of zinc chromate paste is found, replace the bearing with

an airworthy bearing.

(2) If no bearing rotational roughness, corrosion, lack of

lubrication, physical damage, moisture or inadequate drainage due to

build-up of zinc chromate paste is found, thereafter, inspect the

bearing in accordance with this paragraph upon attaining an

additional 150 hours TIS.

(3) For replacement bearings, inspect in accordance with this

paragraph upon attaining 150 hours TIS, unless the bearing reaches

its 300 hour TIS retirement life limit prior to this inspection.

(c) For bearing, P/N 269A5050-73:

(1) Inspect the bearing for corrosion, rust, freedom of

rotation, looseness, binding, nicks, burrs, cracks and lubrication.

Thereafter, inspect the bearing at intervals not to exceed 600 hours

TIS.

(2) As necessary, repack the bearing cavity in accordance with

Schweizer Aircraft Corporation CKP-C-41 ``Installation Instructions

For 269 Series Helicopters, SA-269K-057-1 Main Rotor Thrust Bearing

Kit,'' dated June 9, 1994.

(d) This AD establishes a retirement life of 300 hours TIS for

bearings, P/Ns 269A5050-50 and -51 and a retirement life of 3,000

hours TIS for bearing, P/N 2695050-73. However, bearings, P/Ns

269A5050-50 and -51, with at least 275 hours TIS but less than 300

hours TIS on the effective date of this AD, need not be retired

until or before the accumulation of an additional 25 hours TIS after

the effective date of this AD.

(e) Inspect the thrust bearing nut (nut), P/N 269A1306-5, for

corrosion and physical damage and determine whether the nut has been

modified in accordance with Step III of SSN No. N-59, dated October

9, 1968.

(1) If corrosion or physical damage is found, replace the nut

with an airworthy nut that has been modified in accordance with Step

III of SSN No. N-59, dated October 9, 1968.

(2) If the nut has not been modified, modify the nut in

accordance with Step III of SSN No. N-59, dated October 9, 1968.

(f) Inspect the interior of the main rotor mast (mast) for

corrosion, physical damage, foreign materials, moisture or

inadequate drainage due to a buildup of zinc chromate paste and

determine whether the mast has been modified in accordance with Step

II of SSN No. N-59, dated October 9, 1968 to install a drain hole.

(1) If corrosion or physical damage is found, replace the mast

with an airworthy mast that has been modified in accordance with

Step III of SSN No. N-59, dated October 9, 1968.

(2) If the interior of the mast has foreign materials, moisture

or inadequate drainage due to a buildup of zinc chromate past, clean

the area with a suitable solvent in accordance with Step II of SSN

No. N-59, dated October 9, 1968.

(3) If the mast has not been modified, modify the mast in

accordance with Step III of SSN No. N-59, dated October 9, 1968.

(g) 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, New York Aircraft Certification

Office. Operators shall submit their requests through an FAA

Principal Maintenance Inspector, who may concur or comment and then

send it to the Manager, New York 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 New York Aircraft Certification Office.

(h) 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.

Issued in Fort Worth, Texas, on June 6, 1996.

Larry M. Kelly,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 96-15214 Filed 6-14-96; 8:45 am]

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