AD 98-09-02 ACTIVE

This amendment supersedes an existing airworthiness directive (AD), applicable to McDonnell Douglas Helicopter Systems (MDHS) Model 369 (YOH-6A), 369A (OH-6A), 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, and 369HS helicopters, that currently requires replacing overrunning clutch outer races (outer races) having certain heat treatment numbers. This amendment requires replacing all outer races with airworthy outer races, regardless of the heat treatment number, and is applicable to a particular model helicopter that was not included in the existing AD (Model 500N helicopters). This amendment is prompted by several reports of failed clutch races having heat treatment numbers other than the ones addressed in the earlier AD. The actions specified by this AD are intended to prevent failure of the overrunning clutch assembly outer race, which could result in loss of engine drive to the rotor system and a subsequent forced landing.

Final rule; request for comments

98-09-02 MCDONNELL DOUGLAS HELICOPTER SYSTEMS: Amendment 39-10481. Docket No. 97-SW-52-AD. Supersedes AD 88-10-04, Amendment 39-5897 and AD 88-10-04 R1, Amendment 39-6173.

Applicability: Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, YOH-6A, and OH-6A 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 use the authority provided in paragraph (c) 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 50 hours time-in-service after the effective date of this AD, unless accomplished previously.

To prevent failure of the overrunning clutch assembly outer race, which could result in loss of engine drive to the rotor system and a subsequent forced landing, accomplish the following:

(a) Inspect the overrunning clutch outer race, part number (P/N) 369A5352, to determine its serial number (S/N) in accordance with paragraphs A through C of the Accomplishment Instructions contained in McDonnell Douglas Helicopter Systems Service Information Notice HN-215.2, DN-156.2, EN-46.2, FN-34.2, NN-010, dated March 18, 1997 (service information notice).

(b) Remove any overrunning clutch outer race, P/N 369A5352, having a S/N of 0692 through 0927, and replace it with an airworthy overrunning clutch outer race, P/N 369A5352-5, together with a wave washer, P/N W1593-018, in accordance with the service information notice.

(c) 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, 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 2: 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.

(d) 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.

(e) The inspection and replacement shall be done in accordance with McDonnell Douglas Helicopter Systems Service Information Notice HN-215.2, DN-156.2, EN-46.2, FN-34.2, NN-010, dated April 11, 1997. 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. 530/B11, 5000 E. McDowell Road, Mesa, Arizona 85205-9797. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 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.

(f) This amendment becomes effective on May 6, 1998.

On April 15, 1988, the FAA issued AD 88-10-04, Amendment 39-5897 (53 FR 16384, May 9, 1988) to require replacing outer races, part number (P/N) 369A5352, serial number (S/N) 0692 through 0927, with airworthy outer races in accordance with paragraphs a through g of the Procedures section of McDonnell Douglas Helicopter Company Service Information Notice HN-215/DN-156/EN-46/FN-34, dated March 18, 1988. On March 17, 1989, the FAA issued AD 88-10-04 R1, Amendment 39-6173 (54 FR 12590, March 28, 1989), to limit the scope of AD 88-10-04, to require replacing only outer races, P/N 369A5352, S/N 0692 through 0927, having heat treatment (HT) number HT 255534. The revision to AD 88-10-04 was prompted by a determination that only outer races with heat treatment batch numbers "HT 255534" had been improperly processed during manufacture. That condition, if not corrected, could result in failure of the overrunning clutch assembly outer race, loss of engine drive to the rotor system and a subsequent forced landing.

Since the issuance of that AD and the revision to the AD, MDHS has received additional reports of failed outer races with heat treatment numbers other than HT 255534. Additionally, the FAA has determined that the AD should also be applicable to the Model 500N helicopter. This model was not in existence when the previous AD was issued.

Since an unsafe condition has been identified that is likely to exist or develop on other MDHS Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, YOH-6A, and OH-6A, helicopters of the same type design, this AD supersedes AD 88-10-04 and the revision, AD 88-10-04 R1, to require, within the next 50 hours time-in-service (TIS), removing the outer races, P/N 369A5352, S/N 0692 through S/N 0927, and replacing it with airworthy outer races, P/N 369A5352-5, together with a wave washer, P/N W1593-018. The short compliance time involved is required because the previously described critical unsafe condition can result in a forced landing of the helicopter. Therefore, the replacement of parts is required within the next 50 hours TIS, and this AD must be issued immediately.

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.

The FAA estimates that 2000 MDHS Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, YOH-6A, and OH-6A helicopters of U.S. registry will be affected by this AD, that it will take approximately 2 hours to accomplish the parts replacement, and that the average labor rate is $60 per hour. Required parts will cost approximately $1,614 per helicopter. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $3,468,000.

Comments Invited
Although this action is in theform 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. 97-SW-52-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 ofa 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. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by removing Amendment 39-5897 (53 FR 16384, May 9, 1988) and Amendment 39-6173 (54 FR 12590, March 28, 1989), and by adding a new airworthiness directive (AD), Amendment 39-10481, to read as follows:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 97-SW-52-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. 530/B11, 5000 E. McDowell Road, Mesa, Arizona 85205-9797. This information may be examined at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Mr. Bruce Conze, Aerospace Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Boulevard, Lakewood, California 90712, telephone (562) 627-5261, fax (562) 627-5210.