AD 2000-06-07

This amendment adopts a new airworthiness directive (AD), applicable to Eurocopter Deutschland GMBH (ECD) Model MBB-BK 117 helicopters, that requires changing the retirement life for the tail rotor (output) drive bevel gear (bevel gear). This amendment is prompted by a fatigue analysis of the bevel gear conducted by the manufacturer due to installation of different tail rotor blades. The actions specified by this AD are intended to prevent fatigue failure of the bevel gear, loss of tail rotor drive, and subsequent loss of control of the helicopter.

Final rule

2000-06-07 EUROCOPTER DEUTSCHLAND: Amendment 39-11647. Docket No. 98-SW-77-AD.

Applicability: Model MBB-BK 117 helicopters, serial numbers 7001 through 7250 and 7500 through 7509, with tail rotor (output) drive bevel gear (bevel gear), part number (P/N) 117-12215-01, installed, certificated in any category.

NOTE 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise 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 prevent fatigue failure of the bevel gear, loss of tail rotor drive, and subsequent loss of control of the helicopter, accomplish the following:

(a) Within 100 hours time-in-service (TIS):

(1) Record in the accessory replacement record and historical record "Main Transmission" section the retirement life of 18,500 hours TIS for the bevel gear.

(2) Determine the total hours TIS of the bevel gear. If the total hours TIS cannot be determined, use the operating time of the main transmission.

(b) If the bevel gear's total hours TIS is equal to or greater than 18,400 hours TIS, remove the bevel gear within the next 100 hours TIS and replace it with an airworthy bevel gear. If the bevel gear's total hours TIS is less than 18,400 hours TIS, remove the bevel gear on or before 18,500 hours TIS and replace it with an airworthy bevel gear.

(c) This AD revises the helicopter Airworthiness Limitations section of the maintenance manual by establishing a new retirement life for the bevel gear, P/N 117-12215-01, of 18,500 hours TIS.

(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, Regulations Group, Rotorcraft Directorate, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Regulations Group.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Regulations Group.

(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.

(f) This amendment becomes effective on April 28, 2000.

NOTE 3: The subject of this AD is addressed in Luftfahrt-Bundesamt (Federal Republic of Germany) AD No. 97-350, dated December 18, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to ECD Model MBB-BK 117 helicopters was published in the Federal Register on December 10, 1999 (64 FR 69208). That action proposed to require changing the retirement life for the bevel gear.

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 that the part number of the affected bevel gear has been added to the applicability paragraph and the limitations paragraph to more specifically identify the affected part. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

TheFAA estimates that 130 helicopters of U.S. registry will be affected by this AD, that it will take approximately 0.5 work hour per helicopter to change the retirement life in the records, and 36 work hours to replace the bevel gear. Required parts will cost approximately $14,092 per helicopter. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $2,116,660 to change the retirement life entry and to replace the bevel gear upon reaching 18,500 hours TIS for the entire fleet.

The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.

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 FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas.

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, 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 adding a new airworthiness directive to read as follows: