[Federal Register Volume 59, Number 86 (Thursday, May 5, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-9001]


[[Page Unknown]]

[Federal Register: May 5, 1994]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-184-AD; Amendment 39-8884; AD 94-08-12]

 

Airworthiness Directives; Aerospatiale Model ATR72 Series 
Airplanes, Equipped With Dunlop Main Landing Gear Wheels, Part Number 
AHA1752 Pre Mod 6

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Aerospatiale Model ATR72 series airplanes, that 
requires inspections to detect cracking in the brake side half hub in 
the bearing housing area of certain main landing gear (MLG) wheels, and 
replacement of the MLG wheel, if necessary. This amendment also 
requires the eventual replacement of certain MLG wheels with other 
wheels, as terminating action for the repetitive inspections. This 
amendment is prompted by in-service experience that indicates the 
possibility of fatigue cracking occurring in the subject area. The 
actions specified by this AD are intended to prevent failure of the 
brake side half hub due to fatigue cracking, which could lead to 
separation of the MLG wheel and tire from the axle.

DATES: Effective June 6, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 6, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from Dunlop Limited, Aviation Division, Silverton House, 
Vincent Square, London SW1P 2PL, United Kingdom. This information may 
be examined at the Federal Aviation Administration (FAA), Transport 
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North Capitol 
Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Sam Grober, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-1187; fax (206) 227-1320.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an airworthiness directive (AD) that is 
applicable to certain Aerospatiale Model ATR72 series airplanes was 
published in the Federal Register on November 19, 1993 (58 FR 61038). 
That action proposed to require repetitive eddy current inspections to 
detect cracking in the bearing housing of the brake side half hub of 
Dunlop MLG wheels, part number AHA1752 Pre Mod 6. Additionally, that 
action proposed to require that, if any cracked half hub assemblies are 
detected, the complete wheel must be replaced. If certain improved 
replacement wheels are installed, the repetitive eddy current 
inspections may be discontinued. That action also proposed to require 
the eventual replacement of all MLG wheels having part number AHA1752 
Pre Mod 6 with other (improved) wheels, as terminating action for the 
repetitive inspections.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the single comment received.
    The commenter supports the proposed rule.
    After careful review of the available data, including the comment 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.
    The FAA estimates that 16 airplanes of U.S. registry will be 
affected by this AD, that it will take approximately 2 work hours per 
airplane to accomplish the required actions, and that the average labor 
rate is $55 per work hour. Based on these figures, the total cost 
impact of the inspection actions on U.S. operators is estimated to be 
$1,760, or $110 per airplane, per inspection. Should a cracked half hub 
assembly be found, replacement wheel assemblies will be provided by 
Dunlop at no charge to the operator.
    The required wheel replacement action will require approximately 2 
work hours to accomplish, at an average labor charge of $55 per work 
hour. Replacement parts will be provided by Dunlop at no charge to the 
operators, as part of Dunlop's repair/replacement program. Based on 
these figures, the total cost impact of the replacement actions on U.S. 
operators is estimated to be $1,760, or $110 per airplane.
    The total cost impact figures discussed above are based on 
assumptions that no operator has yet accomplished any of the 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    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 14 CFR part 
39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

94-08-12 Aerospatiale: Amendment 39-8884. Docket 93-NM-184-AD.

    Applicability: Model ATR72 airplanes; equipped with Dunlop main 
landing gear (MLG) wheels, part number AHA1752 Pre Mod 6; 
certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the brake side half hub due to fatigue 
cracking, which could lead to separation of the MLG wheel and tire 
from the axle, accomplish the following:
    (a) At the next tire change after the effective date of this AD, 
or within 60 days after the effective date of this AD, whichever 
occurs later, conduct an eddy current inspection to detect cracking 
in the bearing housing of the brake side half hub of Dunlop MLG 
wheels, part number AHA1752 Pre Mod 6, in accordance with the 
Accomplishment Instructions of Dunlop Limited, Aviation Division, 
Service Bulletin AHA1752-32-1069, dated June 28, 1993.
    (b) If no cracking is detected, repeat the inspection specified 
in paragraph (a) of this AD thereafter at every tire change until 
the requirements of paragraph (d) of this AD are accomplished.
    (c) If any cracking is detected, prior to further flight, 
accomplish one of the following:
    (1) Replace the complete MLG wheel with a serviceable MLG wheel 
having part number AHA1752 Pre Mod 6. Thereafter, repeat the 
inspections specified in paragraph (a) of this AD at every tire 
change. Or
    (2) Replace the complete MLG wheel with a MLG wheel having part 
number AHA1752 Post Mod 6. Such replacement constitutes terminating 
action for the inspection requirements of this AD. Or
    (3) Replace the complete MLG wheel with a MLG wheel having part 
number AHA1890. Such replacement constitutes terminating action for 
the inspection requirements of this AD.
    (d) Within 6 months after the effective date of this AD, replace 
all Dunlop MLG wheels having part number AHA1752 Pre Mod 6, with MLG 
wheels having either part number AHA1752 Post Mod 6 or part number 
AHA1890. Such replacement constitutes terminating action for the 
requirements of this AD.
    (e) 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, Standardization Branch, ANM-113, 
FAA, Transport Airplane Directorate. Operators shall submit their 
requests through an appropriate FAA Principal Maintenance Inspector, 
who may add comments and then send it to the Manager, 
Standardization Branch, ANM-113.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (f) Special flight permits may be issued in accordance with 
Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the 
airplane to a location where the requirements of this AD can be 
accomplished.
    (g) The inspections shall be done in accordance with Dunlop 
Limited, Aviation Division, Service Bulletin AHA1752-32-1069, dated 
June 28, 1993. 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 Dunlop Limited, 
Aviation Division, Silverton House, Vincent Square, London SW1P 2PL, 
United Kingdom. Copies may be inspected at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or 
at the Office of the Federal Register, 800 North Capitol Street, 
NW., suite 700, Washington, DC.
    (h) This amendment becomes effective on June 6, 1994.

    Issued in Renton, Washington, on April 8, 1994.
Darrell M. Pederson,
Acting Manager,Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-9001 Filed 5-4-94; 8:45 am]
BILLING CODE 4910-13-U