Airworthiness directives: McDonnell Douglas,

[Federal Register: April 28, 1999 (Volume 64, Number 81)]

[Proposed Rules]

[Page 22818-22819]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr28ap99-17]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-SW-42-AD]

Airworthiness Directives; McDonnell Douglas Helicopter Systems Model MD-900 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

SUMMARY: This document proposes to supersede an existing airworthiness directive (AD), applicable to McDonnell Douglas Helicopter Systems (MDHS) Model MD-900 helicopters, that currently requires applying specified serial numbers and establishing life limits for certain parts. This proposal is prompted by additional analysis that supports an increase in the life limits of certain parts. The actions specified by this AD are intended to increase the life limits for various parts.

DATES: Comments must be received on or before June 28, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 98-SW-42-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Greg DiLibero, Aerospace Engineer, Aircraft Certification Office, Airframe Branch, FAA, 3960 Paramount Blvd., Lakewood, CA 90712, telephone 562-627-5231, fax number 562-627- 5210.

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 filedin 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. 98-SW-42-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 Regional Counsel, Southwest Region, Attention: Rules Docket No. 98-SW-42-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

Discussion

On June 17, 1997, the FAA issued AD 97-13-09, Amendment 39-10056 (62 FR 34163), applicable to MDHS Model MD-900 helicopters. The AD required applying a specified serial number (S/N) to the following parts: For helicopters with S/N 0002 through 0012, to the mid-forward truss assembly, Part Number (P/N) 900F2401200-102, and to the forward and aft deck fitting assemblies, P/N 900F2401500-103 and 900F2401600-103; for helicopters with S/N 0002 through 0048, to the vertical stabilizer control system (VSCS) bellcrank assemblies, P/N 900F2341712-101, 900FP341712-103, and to the mid-aft truss strut assembly, P/N 900F2401300-103. The AD required reducing the life limits for the nonrotating swashplate assembly, P/N 900C2010192-105, -107, -109, and -111, to 554 hours time- in-service (TIS); the collective drive link assembly, P/N 900C2010207- 101, to 1,480 hours TIS; and the self-aligning, spherical/slider main rotor bearing P/N 900C3010042-103, to 480 hours TIS. The AD required establishing life limits for the VSCS bellcrank assembly, P/N 900FP341712-103, and the bellcrank arm, P/N 900F2341713-101 (used in the VSCS bellcrank assembly, P/N 900F2341712-101), of 2,700 hours TIS. That action was prompted by the need to establish life limits for various parts and to reduce the life limits on other parts to prevent fatigue failure of those parts and subsequent loss of control of the helicopter.

Since the issuance of that AD, additional analysis supports an increase in the life limits for certain parts. The action in that AD of applying S/N's to certain parts and establishing a life limit for the VSCS bellcrank assembly, P/N 900FP341712-103, of 2,700 hours TIS remains the same except that the correct P/N for the bellcrank arm is P/N 900F2341712-101. This document proposes increasing the life limits for the nonrotating swashplate, P/N 900C2010192-105, -107, -109, and - 111, to 1,800 hours TIS; the collective drive link assembly, P/N 900C2010207-101, to 3,307 hours TIS; and the self-aligning, spherical/ slider main rotor bearing, P/N 900C3010042-103, to 2,030 hours TIS. The new life limits are based on modified fatigue spectrums, fatigue tests, and flight strain data. The actions specified in this proposal would increase the life limits for various parts.

Since an unsafe condition has been identified that is likely to exist or

[[Page 22819]]

develop on other MDHS Model MD-900 helicopters of the same type design, the proposed AD would supersede AD 97-13-09 to increase the life limits for certain parts and correct the P/N for the bellcrank, and, as in AD 97-13-09, require applying S/N's to certain parts and establishing a life limit for the VSCS bellcrank assembly,

The FAA estimates that 27 helicopters would be affected by this proposed AD, that it would take approximately 2.5 work hours per helicopter to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $4,050.

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.

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 U.S.C. 106(g), 40113, 44701.

   Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-10056 (62 FR 34163, June 25, 1997), and by adding a new airworthiness directive (AD) to read as follows:

   McDonnell Douglas Helicopter Systems: Docket No. 98-SW-42-AD. Supersedes AD 97-13-09, Amendment 39-10056, Docket No. 96-SW-35-AD.

   Applicability: McDonnell Douglas Helicopter Systems (MDHS) MD- 900 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 request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

   Compliance: Required as indicated, unless accomplished previously. To establish appropriate life limits for various parts, accomplish the following:

   (a) On or before attaining the following life limits, remove from service:

   (1) The nonrotating swashplate assembly, part number (P/N) 900C2010192-105, -107, -109, or -111, on or before 1,800 hours TIS.

   (2) The collective drive link assembly, P/N 900C2010207-101, on or before 3,307 hours TIS.

   (3) The self-aligning, spherical/slider main rotor bearing, P/N 900C3010042-103, on or before 2,030 hours TIS.

   (4) The vertical stabilizer control system (VSCS) bellcrank assembly, P/N 900FP341712-103, and bellcrank arm, P/N 900F2341712- 101, on or before 2,700 hours TIS.

   (b) On or before 100 hours TIS after July 10, 1997, or before October 31, 1999, whichever occurs first:

   (1) For Model MD-900 helicopters with serial numbers (S/N) 900- 00002 through 900-00012, apply the appropriate S/N to the mid- forward truss assembly, P/N 900F2401200-102, and the forward and aft deck-fitting assemblies, P/N 900F2401500-103 and 900F2401600-103.

   (2) For Model MD-900 helicopters with S/N 900-00002 through 900-00048, apply S/N to the left and right VSCS bellcrank assemblies, P/N 900F2341712-101 and 900FP341712-103, and the mid-aft truss strut assembly, P/N 900F2401300-103.

   (3) Apply the S/N as specified in paragraphs (b)(1) and (b)(2) of this AD adjacent to the existing P/N in accordance with the Accomplishment Instructions of MDHS Service Bulletin No. 900-039, Revision 2, dated March 12, 1997.

   (c) This AD revises the Airworthiness Limitations Section of the MD-900 Maintenance Manual by increasing the retirement lives for certain parts.

   Note 2: The Airworthiness Limitations Section of the MD-900 Rotorcraft Maintenance Manual, Reissue 1, Revision 2, dated July 24, 1998, pertains to the subject of this AD.

   (d) 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, Los Angeles 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, Los Angeles Aircraft Certification Office.

   Note 3: 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.

   (e) 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 April 21, 1999. Henry A. Armstrong, Manager, Rotorcraft Directorate, Aircraft Certification Service.

   [FR Doc. 99-10619Filed4-27-99; 8:45 am]

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