Airworthiness Directives; McDonnell Douglas Helicopter Systems and Hughes Helicopters, Inc. Model 369D, E, F, and FF Series Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-SW-13-AD; Amendment 39-9077; AD 94-24-04]

Airworthiness Directives; McDonnell Douglas Helicopter Systems

and Hughes Helicopters, Inc. Model 369D, E, F, and FF Series

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 McDonnell Douglas Helicopter Systems and Hughes

Helicopters, Inc. Model 369D, E, F, and FF series helicopters. This

action requires an initial inspection of the pitch control assembly

lockwasher (lockwasher) for dents at the inner tang inside radius,

application of a torque stripe on the tail rotor swashplate and

locknut, and repetitive inspections of the torque stripe to detect any

locknut slippage. This amendment is prompted by a report that a

lockwasher failed in service and allowed a locknut to loosen. The

actions specified in this AD are intended to prevent failure of the

inner tang of the lockwasher, loss of the locknut, disengagement of the

pitch control assembly, loss of tail rotor control, and subsequent loss

of control of the helicopter.

DATES: Effective December 13, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of December 13, 1994.

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

before January 27, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Rules Docket No. 94-SW-13-AD, 2601 Meacham Blvd., Room 663, Fort Worth,

Texas 76137.

The service information referenced in this AD may be obtained from

McDonnell Douglas Helicopter Systems, Technical Publications, Bldg.

543/B111, 5000 E. McDowell Road, Mesa, Arizona 85205-9797. 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. Brent Bandley, Aerospace Engineer,

Airframe Branch, ANM-123L, Northwest Mountain Region, FAA, Los Angeles

Aircraft Certification Office, 3229 E. Spring Street, Long Beach,

California 90806-2425, telephone (310) 988-5237, fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: This amendment adopts a new airworthiness

directive (AD) that is applicable to McDonnell Douglas Helicopter

Systems (MDHS) and Hughes Helicopters, Inc. (Hughes) Model 369D, E, F,

and FF series helicopters. MDHS received a report that indicated a

pitch control assembly lockwasher (lockwasher), part number (P/N)

MS172209, had failed in service. A subsequent investigation revealed

that some lockwashers appear to have dents at the inner tang inside

radius. The FAA has reviewed the reports and determined that failure of

this tang could allow the locknut to loosen and eventually allow the

pitch control assembly to disengage from the tail rotor assembly.

Should these two tail rotor components separate, the rotorcraft crew

would lose the capability of making necessary anti-torque corrections

through the tail rotor to maintain adequate control of the helicopter.

This condition, if not corrected, could result in failure of the inner

tang of the lockwasher, loss of the locknut, disengagement of the pitch

control assembly, loss of tail rotor control, and subsequent loss of

control of the helicopter.

The FAA has reviewed McDonnell Douglas Helicopter Systems Service

Information Notice (SIN) No. DN-185, EN-78, and FN-64, dated September

23, 1994, which describes procedures for an inspection of the

lockwasher, P/N MS172209, application of a torque stripe on the tail

rotor swashplate and locknut, and repetitive inspections of the pitch

control assembly to detect slippage of the locknut.

Since an unsafe condition has been identified that is likely to

exist or develop on other McDonnell Douglas Helicopter Systems and

Hughes Helicopters, Inc. Model 369D, E, F, and FF series helicopters of

the same type design, this AD is being issued to prevent failure of the

inner tang of the lockwasher, loss of the locknut, disengagement of the

pitch control assembly, loss of tail rotor control, and subsequent loss

of control of the helicopter. This AD requires an initial inspection of

the lockwasher for dents in the inner tang inside radius, application

of a torque stripe on the tail rotor swashplate and locknut, and

repetitive inspections of the torque stripe to detect slippage of the

locknut. Due to the critical need to ensure the integrity of the

lockwasher and the short time-in-service before the initial inspection

is required, this rule must be issued immediately to correct an unsafe

condition in the affected helicopters. The actions are required to be

accomplished in accordance with the SIN described previously.

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 No. 94-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 11.89.

Sec. 39.13 [Amended]

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

to read as follows:

94-24-04 McDonnell Douglas Helicopter Systems (MDHS) and Hughes

Helicopters, Inc. (Hughes): Amendment 39-9077. Docket No. 94-SW-13-

AD.

Applicability: Model 369D, E, F, and FF series helicopters with

pitch control assembly, part number (P/N) 369D21800 or P/N

369D21820, installed, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent failure of the inner tang of the pitch control

assembly lockwasher (lockwasher), loss of the locknut, disengagement

of the pitch control assembly, loss of tail rotor control, and

subsequent loss of control of the helicopter, accomplish the

following:

(a) Within 25 hours time-in-service or 90 calendar days after

the effective date of this AD, whichever occurs first, remove the

tail rotor (T/R) assembly and pitch control assembly from the T/R

gearbox in accordance with the applicable maintenance manual.

(b) Inspect the lockwasher, P/N MS172209, for dents in either

side of the inner tang inside radius as shown in Figure 1 of MDHS

Service Information Notice (SIN) No. DN-185, EN-78, and FN-64, dated

September 23, 1994, using a 5x or higher magnifying glass.

(c) Apply a 0.125 inch-wide torque stripe to the surface of the

locknut and swashplate in accordance with paragraph B and C of Part

II of MDHS SIN No. DN-185, EN-78, and FN-64, dated September 23,

1994, and reinstall the T/R assembly and pitch control assembly into

the T/R gearbox in accordance with the applicable maintenance

manual.

(d) Inspect the torque stripe for slippage at intervals not to

exceed 100 hours time-in-service. If any slippage is detected,

replace the lockwasher with an airworthy lockwasher in accordance

with the applicable maintenance manual. Reapply the 0.125 inch-wide

torque stripe to the surface of the locknut and swashplate.

(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 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: 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 21.197 and 21.199) to operate the helicopter to a location where

the requirements of this AD can be accomplished.

(g) The inspections shall be done in accordance with McDonnell

Douglas Helicopter Systems Service Information Notice No. DN-185,

EN-78, and FN-64, dated September 23, 1994. 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 McDonnell Douglas Helicopter Systems, Technical

Publications, Bldg. 543/B111, 5000 E. McDowell Road, Mesa, Arizona

85205-9797. 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 December 13, 1994.

Issued in Fort Worth, Texas, on November 16, 1994.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 94-28938 Filed 11-25-94; 8:45 am]

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