Airworthiness Directives: Sikorsky Aircraft Model S-58T Series Helicopters

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-SW-07-AD; Amendment 39-8935; AD 94-12-07]

Airworthiness Directives: Sikorsky Aircraft Model S-58T Series

Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to Sikorsky Aircraft Model S-58T series helicopters,

that currently requires a one-time inspection of the engine drive shaft

assembly (drive shaft assembly) for cracks and loose balance weights.

This amendment requires initial and repetitive visual and florescent

penetrant inspections of the drive shaft assembly for cracks and

improperly installed rivets. This amendment is prompted by three

reported incidents of loose or missing drive shaft assembly balance

weights and two reported incidents of fatigue cracks on the drive shaft

assembly near the balance weight rivet hole. The actions specified by

this AD are intended to prevent failure of the drive shaft assembly,

loss of power to the rotor system, and a subsequent forced landing of

the helicopter.

DATES: Effective August 1, 1994.

The incorporation by reference of certain publications listed in

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

of August 1, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Sikorsky Aircraft Division, United Technologies

Corporation, North Main Street, Stratford, Connecticut 06601. This

information may be examined at the Federal Aviation Administration

(FAA), Office of the Assistant Chief Counsel, 2601 Meacham Boulevard,

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. Terry Fahr, Aerospace Engineer,

Boston Aircraft Certification Office, FAA, Engine and Propeller

Directorate, Aircraft Certification Service, 12 New England Executive

Park, Burlington, Massachusetts 01803, telephone (617) 238-7155, fax

(617) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) by superseding AD 90-10-02,

Amendment 39-6590 (55 FR 18305, May 2, 1990), which is applicable to

Sikorsky Aircraft Model S-58T series helicopters, was published in the

Federal Register on August 31, 1993 (58 FR 45859). That action proposed

to require initial and repetitive visual and florescent penetrant

inspections of the engine drive shaft assembly for cracks and loose

balance weights, and replacement as necessary.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. No comments were received on the

proposal or the FAA's determination of the cost to the public. The FAA

has determined that air safety and the public interest require the

adoption of the rule as proposed, except for editorial changes.

The FAA estimates that 58 helicopters of U.S. registry will be

affected by this AD, that it will take approximately 18 work hours per

helicopter to accomplish the required actions, and that the average

labor rate is $55 per work hour. Based on these figures, the total cost

impact of the AD on U.S. operators is estimated to be $57,420.

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.

For the reasons discussed above, I certify that this action (1) is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it 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 removing Amendment 39-6590 (55 FR

18305, May 2, 1990), and by adding a new airworthiness directive (AD),

Amendment 39-8935, to read as follows:

AD 94-12-07 Sikorsky Aircraft: Amendment 39-8935. Docket Number 93-

SW-07-AD. Supersedes AD 90-10-02, Amendment 39-6590.

Applicability: Model S-58T series helicopters, equipped with

engine drive shaft assembly (drive shaft assembly), part number (P/

N) 58350-10030-045 and subassembly P/N 58350-10030-046, or drive

shaft assembly, P/N 58350-10030-047 and subassemblies 58350-10030-

048 and -049, certificated in any category. The subassembly part

numbers will appear adjacent to the 58350-10030-045 and 58350-10030-

047 drive shaft assembly part numbers.

Compliance: Required as indicated, unless accomplished

previously. To prevent failure of the drive shaft assembly, loss of

power to the rotor system, and a subsequent forced landing of the

helicopter, accomplish the following:

(a) Within the next 25 hours' time-in-service (TIS) after the

effective date of this AD, or at the next removal of the drive shaft

assembly, P/N 58350-10030-045 and subassembly -046, or P/N 58350-

10030-047 and subassemblies -048 and -049, whichever comes first--

(1) Remove and inspect the drive shaft assembly for proper

installation of rivets, loose balance weights, and cracks in

accordance with paragraphs 2.A.(1), (2), and (4) of the

Accomplishment Instructions of Sikorsky Alert Service Bulletin (ASB)

No. 58B35-31A, Revision A, dated February 17, 1993.

(2) If a crack, loose balance weight, or improper rivet

installation is found, replace the drive shaft assembly with an

airworthy drive shaft assembly.

(b) Within the next 25 hours' TIS after compliance with

paragraph (a) of this AD, and at every 25 hours' TIS thereafter,

visually inspect the drive shaft assembly for cracks in accordance

with paragraph 2.B. of the Accomplishment Instructions of ASB No.

58B35-31A, Revision A, dated February 17, 1993.

(c) For drive shaft assembly, P/N 58350-10030-045 and

subassembly -046, that have not been reworked in accordance with

Sikorsky Overhaul Repair Instruction (ORI) No. 58350-001, Revision

A, dated November 18, 1992, within 250 hours' TIS after the

inspections required by paragraph (a) of this AD, and thereafter at

intervals not to exceed 250 hours' TIS, remove and inspect the drive

shaft assembly in accordance with paragraph 2.C. of the

Accomplishment Instructions of ASB No. 58B35-31A, Revision A, dated

February 17, 1993.

(d) For drive shaft assembly, P/N 58350-10030-047 and

subassemblies -048 and -049, and additionally, for drive shaft

assembly, P/N 58350-10030-045 and subassembly -046, that have been

reworked in accordance with ORI No. 58350-001, Revision A, dated

November 18, 1992, within 2,500 hours' TIS after the inspections

required by paragraph (a) of this AD, and thereafter at intervals

not to exceed 2,500 hours' TIS, remove and inspect the drive shaft

assembly in accordance with subparagraph 2.D of the Accomplishment

Instructions of ASB No. 58B35-31A, Revision A, dated February 17,

1993.

(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, Boston 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, Boston Aircraft Certification Office.

Note: Information concerning the existence of approved

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

obtained from the Boston 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 and replacement, if necessary, shall be done

in accordance with Sikorsky Alert Service Bulletin No. 58B35-31A,

Revision A, dated February 17, 1993. 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

Sikorsky Aircraft Division, United Technologies Corporation, North

Main Street, Stratford, Connecticut 06601. Copies may be inspected

at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham

Boulevard, 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 August 1, 1994.

Issued in Fort Worth, Texas, on June 2, 1994.

Larry M. Kelly,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 94-15146 Filed 6-24-94; 8:45 am]

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