Airworthiness Directives; Enstrom Helicopter Corporation Model TH-28 and 480 Helicopters

[Federal Register Volume 66, Number 238 (Tuesday, December 11, 2001)]
[Rules and Regulations]
[Pages 63915-63916]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-30499]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-SW-27-AD; Amendment 39-12554; AD 2001-25-02]
RIN 2120-AA64


Airworthiness Directives; Enstrom Helicopter Corporation Model 
TH-28 and 480 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) for 
Enstrom Helicopter Corporation (EHC) Model TH-28 and 480 helicopters. 
This AD requires establishing a life limit for certain upper and lower 
main rotor hub plates of 5000 hours time-in-service (TIS), creating a 
component history card or equivalent record, and replacing each main 
rotor hub plate (hub plate) having 5000 or more hours TIS with an 
airworthy hub plate. This AD is prompted by a recent reliability-based 
stress analysis that indicates a 5000-hour TIS life limit should be 
imposed on certain hub plates. The actions specified by this AD are 
intended to prevent failure of a hub plate, loss of control of the main 
rotor, and subsequent loss of control of the helicopter.

EFFECTIVE DATE: January 15, 2002.

FOR FURTHER INFORMATION CONTACT: Joseph McGarvey, Fatigue Specialist, 
FAA, Chicago Aircraft Certification Office, Airframe and Administrative 
Branch, 2300 East Devon Ave., Des Plaines, Illinois 60018, telephone 
(847) 294-7136, fax (847) 294-7834.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an AD for EHC Model 
TH-28 and 480 helicopters was published in the Federal Register on 
September 18, 2001 (66 FR 48102). That action proposed establishing a 
life limit of 5000 hours TIS for both upper and lower hub plates, part 
number (P/N) 28-14280-1 and 28-14281-1. Also proposed was replacing hub 
plates, P/N 28-14280-1 and 28-14281-1, having 5000 or more hours TIS 
with airworthy hub plates.
    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.
    The FAA estimates that 4 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 10 work hours per 
helicopter to replace the hub plates, and that the average labor rate 
is $60 per work hour. Creating a component history or equivalent record

[[Page 63916]]

would take approximately 2 hours. Required parts will cost 
approximately $5350 to install hub plates, P/N 28-14280-3 and 28-14281-
3 and $5000 to install hub plates, P/N 28-14280-5 and 28-14281-5, per 
helicopter. Based on these figures, the total cost impact of this AD on 
U.S. operators is estimated to be $24,280 maximum, assuming that all 
hub plates are replaced and that hub plates, P/N 28-14280-3 and 28-
14281-3, are installed.
    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.


Sec. 39.13  [Amended]

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

2001-25-02  Enstrom Helicopter Corporation: Amendment 39-12554. 
Docket No. 2001-SW-27-AD.

    Applicability: Model TH-28 and 480 helicopters, with upper hub 
plate, part number (P/N) 28-14280-1, and lower hub plate, P/N 28-
14281-1, 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 (c) 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 failure of a hub plate, loss of control of the main 
rotor, and subsequent loss of control of the helicopter, accomplish 
the following:
    (a) Within 30 days after the effective date of this AD, for 
upper hub plate, P/N 28-14280-1, and for lower hub plate, P/N 28-
14281-1, create a component history card or equivalent record, and 
determine the total hours time-in-service (TIS). Thereafter, record 
the hours TIS for each hub plate and replace each hub plate having 
5000 or more hours TIS as follows:
    (1) Install hub plates, P/N 28-14280-3 and 28-14281-3, on 
helicopters with main rotor damper, P/N 28-14375-8.
    (2) Install hub plates, P/N 28-14280-5 and 28-14281-5, on 
helicopters with main rotor damper, P/N 28-14375-10.
    (b) This AD revises the Limitations section of the applicable 
maintenance manual by establishing a life limit of 5000 hours TIS 
for the upper hub plate, P/N 28-14280-1, and for the lower hub 
plate, P/N 28-14281-1.
    (c) 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, Chicago Aircraft Certification 
Office (ACO), FAA. Operators shall submit their requests through an 
FAA Principal Maintenance Inspector, who may concur or comment and 
then send it to the Manager, Chicago ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Chicago ACO.

    (d) Special flight permits may be issued in accordance with 14 
CFR 21.197 and 21.199 to operate the helicopter to a location where 
the requirements of this AD can be accomplished.
    (e) This amendment becomes effective on January 15, 2002.

    Issued in Fort Worth, Texas, on November 30, 2001.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 01-30499 Filed 12-10-01; 8:45 am]
BILLING CODE 4910-13-U

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