[Federal Register Volume 61, Number 214 (Monday, November 4, 1996)]
[Proposed Rules]
[Pages 56640-56641]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-28168]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 61, No. 214 / Monday, November 4, 1996 / 
Proposed Rules  

[[Page 56640]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-SW-05-AD]


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is 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. This proposal would 
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; and would also require 
creating a main rotor transmission component log card, if none is 
available, and making a notation on the main rotor transmission 
component log card if a ring gear is changed. This proposal 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 the proposed AD are intended to 
prevent failure of the ring gear, loss of drive to the main rotor 
gearbox, and a subsequent forced landing.

DATES: Comments must be received by January 3, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 96-SW-05-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137. Comments may be inspected at this location between 9:00 
a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.
    The service information referenced in the proposed rule 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 Assistant Chief Counsel, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas.

FOR FURTHER INFORMATION CONTACT: Mr. Raymond Reinhardt, Aerospace 
Engineer, New York Aircraft Certification Office, FAA, 181 South 
Franklin Ave., Room 202, Valley Stream, New York 11581, telephone (516) 
256-7532, fax (516) 568-2716.

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 filed in 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. 96-SW05-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 Assistant Chief Counsel, Attention: Rules 
Docket No. 96-SW-05-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 
76137.

Discussion

    This document proposes the adoption of a new AD that is applicable 
to Schweizer Aircraft Corporation Model 269A, A1, B, and C, and TH-55A 
helicopters, with ring gear, part number (P/N) 269A5104-5, installed. 
This proposal is prompted by 35 reports of failures of the ring gear 
since July 1975. The failures were attributed to single tooth distress 
as a result of improper gear tooth spacing during the manufacturing of 
the gear. The tooth spacing variation forces the tooth that is 
improperly spaced to accept more of the load at longer duration or at a 
location that leads to higher point contact loads and surface distress. 
This surface distress eventually leads to subsurface cracking and 
finally fatigue failure. One of these failures resulted in loss of 
drive to the main rotor gearbox resulting in a forced autorotational 
landing of the helicopter. Three failures caused the ``XMSN TEMP./
PRESS'' red warning indicator on the main instrument panel to 
illuminate due to low oil pressure caused by a secondary failure of the 
main transmission lube pump. The other failures resulted only in 
increased noise and/or vibration. This proposal would 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 
serviceable parts or transmissions; and within the next 50 hours TIS or 
at the next annual inspection, whichever occurs first. Thereafter, the 
notice proposes repetitive inspections at each 50 hours TIS inspection 
in accordance with the manufacturer's service bulletin. The actions 
specified by the proposed AD are intended to prevent failure of the 
ring gear, loss of drive to the main rotor gearbox, and a subsequent 
forced landing.
    The FAA has reviewed Schweizer Aircraft Corporation Service 
Bulletin B-

[[Page 56641]]

244.2, dated February 19, 1996, which describes procedures for 
inspection of the ring gear for surface deterioration, pitting, 
wearing, cracking, or corrosion, and replacement of the main 
transmission if surface deterioration, pitting, wearing, cracking, or 
corrosion is found.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Schweizer Aircraft Corporation Model 269A, A-
1, B, and C, and TH-55A helicopters of the same type design, the 
proposed AD would require an inspection of the ring gear for surface 
deterioration, pitting, wearing, cracking, or corrosion, and 
replacement of the ring gear with ring gear, P/N 269A5104-7, if surface 
deterioration, pitting, wearing, cracking, or corrosion is found; and, 
creation of a main rotor transmission component log card if none is 
available, and a notation on the main rotor transmission component log 
card if a ring gear, P/N 269A5104-7, is installed. Schweizer Aircraft 
Corporation has blank component log cards available for main rotor 
transmissions that do not currently have a component log card. The 
actions would be required to be accomplished in accordance with the 
service bulletin described previously.
    The FAA estimates that 87 helicopters of U.S. registry would be 
affected by this proposed AD, that it would 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 would cost 
approximately $6,400 per ring gear and $1,219 per overhaul kit. Based 
on these figures, the total cost impact of the proposed 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 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 adding a new airworthiness directive 
to read as follows:

Schweizer Aircraft Corporation: 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, 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, 
pitting, 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, pitting, 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.
    (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.
    (e) Installation of a ring gear, P/N 269A5104-7, is considered a 
terminating action for this AD and must be annotated on a Schweizer 
Aircraft Corporation 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.

    Issued in Fort Worth, Texas, on October 25, 1996.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 96-28168 Filed 11-1-96; 8:45 am]
BILLING CODE 4910-13-U