[Federal Register Volume 61, Number 57 (Friday, March 22, 1996)]
[Proposed Rules]
[Pages 11784-11786]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-6882]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-CE-75-AD]


Airworthiness Directives; Aerospace Technologies of Australia, 
Nomad Models N22B, N22S, and N24A Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain Aerospace Technologies of Australia 
(ASTA) Nomad Models N22B, N22S, and N24A airplanes. The proposed action 
would require repetitively inspecting the tailplane stabilizer center 
section and repairing any cracked tailplane structure. This proposal 
also provides an optional modification as a terminating action, after 
an inspection in which no cracks are found. A tailplane failure on one 
of the affected airplanes prompted the proposed action. The actions 
specified by the proposed AD are intended to prevent cracking in the 
stabilizer center section, which, if not detected and corrected, could 
result in tailplane failure and loss of control of the airplane.

DATES: Comments must be received on or before June 28, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 95-CE-75-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106. Comments may be inspected at 
this location between 8 a.m. and 4 p.m., Monday through Friday, 
holidays excepted.
    Service information that applies to the proposed AD may be obtained 
from AeroSpace Technologies of Australia, Limited, ASTA DEFENCE, 
Private Bag No. 4, Beach Road Lara 3212, Victoria, Australia. This 
information also may be examined at the Rules Docket at the address 
above.

FOR FURTHER INFORMATION CONTACT: Mr. Ron Atmur, Aerospace Engineer, 
Aircraft Certification Office, FAA, 3960 Paramount Blvd., Lakewood, 
California, 90712; telephone (310) 627-5224; facsimile (310) 627-5210;

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 that summarizes 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. 95-CE-75-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, Central Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 95-CE-75-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.

Discussion

    The Civil Airworthiness Authority (CAA), which is the airworthiness 
authority for Australia, has notified the FAA that an unsafe condition 
may exist on ASTA Nomad N22 and N24 series airplanes that have not 
incorporated ASTA Modification N663 and N768. The Australian CAA 
reported one accident and several incidents of cracking in the 
tailplane stabilizer center section of the airplanes.
    The accident was caused by the loss of a tailplane during flight. 
Investigation of the accident revealed undetected cracking around the 
center lightening hole which was significantly accelerated by long 
periods of engine ground running. Subsequent testing also indicated 
that engine ground running at moderate to high power settings during 
ground maneuvers create unexpected fatigue loads and accelerate the 
crack growth.
    ASTA has issued Nomad Alert Service Bulletin (Nomad SB) ANMD-55-26, 
Revision 8, dated April 15, 1994, which specifies procedures for 
inspecting and modifying the stabilizer center section on Nomad Models 
N22B, N22S, and N24A airplanes. Accomplishment of these procedures 
incorporates Modifications (Mod.) N663 and N768. Mod. N663 reworks the 
horizontal stabilizer to incorporate a strengthened main spar assembly 
that includes a gust stop spring box and modified mass balance arm. The 
trim tab hinges are moved 0.17 inches aft and farings are added to the 
bottom skin of the horizontal stabilizer to permit increased trim tab 
movement. Mod. N768 replaces the pivot brackets, attachment bolts, and 
spar web doubler with strengthened components.
    The Australian CAA classified this service bulletin as mandatory 
and issued AD/GAF-N22/58 amdt 4, issued November, 1991, in order to 
assure the continued airworthiness of these airplanes in Australia.
    These airplane models are manufactured in Australia and are type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement between Australia and 
the United States. Pursuant to this bilateral airworthiness agreement, 
the Australian CAA has kept the FAA informed of the above-described 
situation. The FAA has examined the findings of the Australian

[[Page 11785]]
CAA, reviewed all available information, and determined that AD action 
is necessary for airplanes of this type design that are certificated 
for operation in the United States.
    Since an unsafe condition has been identified that is likely to 
exist or develop in other ASTA Nomad Models N22B, N22S, and N24A 
airplanes of the same type design that do not have Modifications N663 
and N768 incorporated in the area of the tailplane stabilizer center 
section, the proposed AD would require inspecting (using both visual 
and eddy current methods) the tailplane stabilizer section for cracks 
and, prior to further flight, repairing any cracked tailplane 
stabilizer center section. This AD also provides the option of 
modifying the tailplane stabilizer center section (Mod. N663 and N768) 
as a terminating action. Accomplishment of the proposed inspection 
would be in accordance with Nomad SB ANMD-55-26, Revision 8, dated 
April 15, 1994. If the tailplane stabilizer center section is found 
cracked, the repair would be in accordance with a scheme obtained from 
the Los Angeles Aircraft Certification Office.
    The FAA estimates that 15 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 15 
workhours per airplane to accomplish the proposed action, and that the 
average labor rate is approximately $60 an hour. The total cost impact 
of the proposed AD upon U.S. operators of the affected airplanes is 
estimated to be $13,500. This figure only includes the cost for the 
initial inspection and does not include replacement costs if the 
tailplane stabilizer center section is found cracked, nor does it 
include repetitive inspection costs. Additionally, the FAA has no way 
of determining how many tailplane stabilizer center sections may be 
cracked or how many repetitive inspections each owner/operator may 
incur over the life of the airplane.
    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 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) 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 has been placed 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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

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

Aerospace Technologies of Australia (ASTA): Docket No. 95-CE-75-AD.

    Applicability: Nomad Models N22B, N22S, and N24A airplanes (all 
serial numbers), certificated in any category, that have not 
incorporated ASTA Modification N663 and N768 in the area of the 
tailplane stabilizer.

    Note 1: This AD applies to each airplane 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 airplanes 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 (d) 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 within the next 100 hours time-in-service 
(TIS) after the effective date of this AD, unless already 
accomplished, and thereafter at intervals not to exceed 100 hours 
TIS.
    To prevent cracking in the tailplane stabilizer center section, 
which, if not detected and corrected, could result in tailplane 
failure and loss of control of the airplane, accomplish the 
following:
    (a) Inspect the tailplane stabilizer center section and center 
lightening hole for cracks (using both visual and eddy current 
methods) in accordance with section ``C. Description, (1) Part 1--
Inspection.'' of ASTA Nomad Alert Service Bulletin (Nomad SB) ANMD-
55-26, Revision 8, dated April 15, 1994.
    (b) If cracks are found during any inspection required by this 
AD, prior to further flight, repair the stabilizer center section in 
accordance with a repair scheme obtained from the manufacturer 
through the Manager, Los Angeles Aircraft Certification Office, at 
the address specified in paragraph (d).
    (1) This repair scheme does not eliminate the repetitive 
inspection requirement.
    (2) The repetitive inspection requirement of this AD may be 
terminated by incorporating both Modification (Mod.) N663 and N768 
in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Nomad 
SB ANMD-55-26, Revision 8, dated April 15, 1994. These modifications 
may only be incorporated, prior to further flight, after any 
inspection provided no cracks are found.

    (3) Modifications N663 and N768 may also be incorporated as 
terminating action to the repetitive inspections of this AD on 
airplanes that have cracks repaired in the tailplane stabilizer 
center section provided the modifications are incorporated prior to 
further flight after an inspection where no cracks were found.
    Note 2: Mod. N663 reworks the horizontal stabilizer to 
incorporate a strengthened main spar assembly that includes a gust 
stop spring box and modified mass balance arm. The trim tab hinges 
are moved 0.17 inches aft and farings are added to the bottom skin 
of the horizontal stabilizer to permit increased trim tab movement. 
Mod. N768 incorporates Mod. 663 and replaces the pivot brackets, 
attachment bolts, and spar web doubler with strengthened components.

    (c) 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 airplane to a location where 
the requirements of this AD can be accomplished.
    (d) An alternative method of compliance or adjustment of the 
initial or repetitive compliance times that provides an equivalent 
level of safety may be approved by the Manager, Los Angeles Aircraft 
Certification Office, FAA, 3960 Paramount Blvd., Lakewood, 
California, 90712. The request shall be forwarded through an 
appropriate FAA Maintenance Inspector, who may add comments and then 
send it to the Manager, Los Angeles Aircraft Certification Office.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles Aircraft Certification Office.

    (e) All persons affected by this directive may obtain copies of 
the document referred to herein upon request to AeroSpace 
Technologies of Australia, Limited, ASTA DEFENCE, Private Bag No. 4, 
Beach Road Lara 3212, Victoria, Australia; or may examine this/these 
document(s) at the FAA, Central Region, Office of the Assistant 
Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 
64106.


[[Page 11786]]

    Issued in Kansas City, Missouri, on March 15, 1996.
James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-6882 Filed 3-21-96; 8:45 am]
BILLING CODE 4910-13-P