[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]
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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.
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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
