AD 97-29237

[Federal Register Volume 62, Number 214 (Wednesday, November 5, 1997)] [Rules and Regulations] [Pages 59781-59783] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 97-29237]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-SW-05-AD; Amendment 39-10194; AD 97-23-06] RIN 2120-AA64

Airworthiness Directives; Schweizer Aircraft Corporation Model 269A, A-1, B, and C, and TH-55A Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), applicable to Schweizer Aircraft Corporation Model 269A, A-1, B, and C, and TH-55A helicopters, with a certain main rotor transmission ring gear (ring gear) installed, that requires inspections of the ring gear teeth for surface deterioration which includes pitting, excessive wearing, cracking or corrosion, and replacement of the ring gear if such ring gear teeth surface deterioration is found; and also requires creating a main rotor transmission component log card (log card), if none is available, and making a notation on the log card if a ring gear is changed. This amendment is prompted by reports of failures of the ring gear due to single tooth distress as a result of improper gear tooth spacing during the manufacturing of the ring gear. The actions specified by this AD are intended to prevent failure of the ring gear, loss of drive to the main rotor gearbox, and a subsequent forced landing.

DATES: Effective December 10, 1997. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 10, 1997.

ADDRESSES: The service information referenced in this AD may be obtained from Schweizer Aircraft Corporation, P.O. Box 147, Elmira, NY 14902, ATTN: Publications Dept. This information may be examined 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.

FOR FURTHER INFORMATION CONTACT: Mr. Raymond Reinhardt, Aerospace Engineer, New York Aircraft Certification Office, FAA, 10 Fifth Street, 3rd Floor, Valley Stream, New York 11581, telephone (516) 256-7532, fax (516) 568-2716.

SUPPLEMENTARY INFORMATION: 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 Schweizer Aircraft Corporation Model 269A, A-1, B, and C, and TH-55A helicopters was published in the Federal Register on November 4, 1996 (61 FR 56640). That action proposed to require inspections of the ring gear teeth for pitting, wearing, cracking or corrosion, and replacement of the ring gear if such ring gear teeth surface deterioration is found. The proposed inspections would be accomplished before further flight if clicking, tapping, or other unusual noises, or unusual vibration is detected while operating the helicopter, or if metal particles are found on the magnetic drain plug during routine maintenance; or, upon installation of replacement transmissions with the affected ring gear; and within the next 50 hours time-in-service (TIS) or at the next annual inspection, whichever occurs first. Thereafter, the notice proposes repetitive inspections at intervals not to exceed 50 hours TIS in accordance with the manufacturer's service bulletin. Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. The one commenter states that all ring gears, P/N 269A5104-005, should not be affected by the AD, but that only ring gears, P/N 269A5104-005, manufactured by Eastern Gear Corporation (EGC) and ACR Industries (ACR), should be affected. The same commenter also states that the use of the term ``wearing'' in the proposed AD needs further amplification because all gear teeth will exhibit wear after some time in service. This wear is normally very minor, but the inference of the proposed AD could lead one to believe that ANY wear is unacceptable. The FAA concurs with both comments and the requirements of this AD are changed accordingly. The applicability paragraph has been revised to specify only those gears manufactured by EGS and ACR. The word ``excessive'' has been added before the word ``wearing'' since all gears will experience some wear after some time in service. The inspection for wear, including what constitutes ``excessive wear'', is contained in the Basic Helicopter Maintenance Instructions, Section 10, which is referenced in Schweizer

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Service Bulletin B-244.2, dated February 19, 1996. Additionally, since the issuance of the proposal, the manufacturer received a report of a failure of a ring gear, P/N 269A5104-7, which is the same part-numbered ring gear specified in the proposal as an airworthy replacement. Since that report, the manufacturer has changed the material properties in the manufacturing of ring gears beginning with serial number S2100 or higher. Therefore, the AD is changed to specify that only ring gears, P/N 269A5104-7, S/N S2100 or higher, are acceptable as replacements. After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously and with other non-substantive changes. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. The FAA estimates that 87 helicopters of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per helicopter to accomplish the initial inspections, 0.5 hours to create a main rotor transmission component log card, and 28 work hours if removal and replacement of the ring gear is required, and that the average labor rate is $60 per work hour. Required parts will cost approximately $6,400 per ring gear and $1,219 per overhaul kit. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $822,063, assuming creation of a component log card and replacement of the ring gear in the entire fleet is necessary. 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 USC 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive to read as follows:

AD 97-23-06 Schweizer Aircraft Corporation: Amendment 39-10194. Docket No. 96-SW-05-AD.

Applicability: Model 269A, A-1, B, and C, and TH-55A helicopters, with main rotor transmission ring gear (ring gear), part number (P/N) 269A5104-5, identified by the letters EGC (Eastern Gear Corporation), ACR (ACR Industries), or the manufacturer code number 23751 (EGC) or 57152 (ACR), 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 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 (f) 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 as indicated, unless accomplished previously. To prevent failure of the ring gear, loss of drive to the main rotor gearbox, and a subsequent forced landing, accomplish the following: (a) Inspect the ring gear teeth for surface deterioration which includes pitting, excessive wearing, cracking or corrosion in accordance with Schweizer Service Bulletin B-244.2, dated February 19, 1996, as follows: (1) Before further flight, if a clicking or tapping sound or other unusual noise or unusual vibration is detected while operating the helicopter, or if a metal particle is found on the magnetic drain plug during routine maintenance; (2) Before installing a main rotor transmission which contains an affected ring gear on the helicopter; (3) Within the next 50 hours time-in-service (TIS) after the effective date of this AD, or at the next annual inspection, whichever occurs first. (b) Thereafter, inspect the ring gear teeth at intervals not to exceed 50 hours TIS in accordance with Schweizer Service Bulletin B- 244.2, dated February 19, 1996. (c) If surface deterioration which includes pitting, excessive wearing, cracking or corrosion is discovered, before further flight, remove the transmission from service and replace the ring gear with a ring gear, P/N 269A5104-7, serial number (S/N) S2100 or higher number. (d) At the next main rotor transmission overhaul, remove and replace the ring gear, P/N 269A5104-5, identified on the face of the ring gear by the letters EGC, ACR, or the manufacturer code number 23751 (EGC) or 57152 (ACR) and replace it with a ring gear, P/N 269A5104-7, S/N S2100 or higher number. (e) Installation of a ring gear, P/N 269A5104-7, S/N S2100 or higher number constitutes a terminating action for the requirements of this AD and must be annotated on a component log card. A new component log card must be created if a component log card is not in the applicable maintenance records. (f) 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, New York 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, New York 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 New York Aircraft Certification Office.

(g) 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, provided no clicking or tapping sound or other unusual noise or unusual vibration was detected on any previous flight. (h) The inspections shall be done in accordance with Schweizer Service Bulletin B-244.2, dated February 19, 1996. 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 Schweizer Aircraft Corporation, P.O. Box 147, Elmira, NY 14902, ATTN: Publications Dept. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort

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Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (i) This amendment becomes effective on December 10, 1997.

Issued in Fort Worth, Texas, on October 30, 1997. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 97-29237 Filed 11-4-97; 8:45 am] BILLING CODE 4910-13-U