AD Amdt-39-10194

[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 [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[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

[[Page 59782]]

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

[[Page 59783]]

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