[Federal Register Volume 63, Number 139 (Tuesday, July 21, 1998)]
[Proposed Rules]
[Pages 39053-39054]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-19327]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-CE-62-AD]
RIN 2120-AA64


Airworthiness Directives; Air Tractor, Inc. AT-300, AT-400, and 
AT-500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to supersede Airworthiness Directive 
(AD) 96-23-19, which currently requires installing a new flap actuator 
overtravel stop and a roll pin through the overtravel stop and jack 
screw on certain Air Tractor, Inc. (Air Tractor) Models AT-300, AT-400, 
and AT-500 series airplanes. The proposed AD would require replacing 
the existing flap actuator overtravel stop with a new one of improved 
design. The proposed AD is the result of reports of the jack screw 
breaking through the roll pin hole on three of the affected airplanes 
that were already in compliance with AD 96-23-19. The actions specified 
by the proposed AD are intended to prevent interference between the 
flap pushrod and the aileron pushrod caused by the flap actuator 
overtravel nut disengaging, which could result in loss of aileron 
control.

DATES: Comments must be received on or before September 18, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 98-CE-62-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 Air Tractor, Inc., P. O. Box 485, Olney, Texas 76374. This 
information also may be examined at the Rules Docket at the address 
above.

FOR FURTHER INFORMATION CONTACT: Mr. Bob May, Aerospace Engineer, FAA, 
Aircraft Certification Office, 2601 Meacham Boulevard, Fort Worth, 
Texas 76193-0150; telephone: (817) 222-5156; facsimile: (817) 222-5960.

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. 98-CE-62-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 Regional Counsel, Attention: 
Rules Docket No. 98-CE-62-AD, Room 1558, 601 E. 12th Street, Kansas 
City, Missouri 64106.

Discussion

    AD 96-23-19, Amendment 39-9823 (61 FR 58985, November 11, 1996), 
currently requires installing a new flap actuator overtravel stop and a 
roll pin through the overtravel stop and jack screw on certain Air 
Tractor Models AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-
401A, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-
502B, and AT-503A airplanes. Accomplishment of these installations is 
required in accordance with Snow Engineering Co. Service Letter #140, 
dated November 27, 1995, Revised October 10, 1996.
    AD 96-23-19 was the result of reports of incidents involving Air 
Tractor Models AT-402 and AT-502 airplanes, where the flap actuator 
overtravel stop nut disengaged from the jack screw. The flap pushrod 
pressed against the aileron pushrod, which caused difficulty in moving 
the ailerons.

Actions Since Issuance of Previous Rule

    The FAA has received reports of incidents of the jack screw 
breaking through the roll pin hole on three of the affected airplanes 
that were already in compliance with AD 96-23-19. Two cases of the 
control system binding up in the field prompted the FAA to investigate 
this condition with the following information revealed:

--The down flap limit switch must be inoperative;
--The mechanical overtravel stop nut must have fallen off; and
--The flaps must be driven down past the limit switch position to the 
maximum flap position where the aileron pushrods begin to bind.

    The Snow Engineering Co. (the parent company of Air Tractor) and 
the FAA have simulated this combination of stop nut failure and limit 
switch failure on factory airplanes through a laboratory environment.
    This condition, if not corrected in a timely manner, could result 
in difficulty in moving the ailerons with possible loss of aileron 
control.

Relevant Service Information

    The Snow Engineering Co. has issued Service Letter #165, dated May 
15, 1998, which specifies procedures for replacing the flap actuator 
overtravel stop with one of improved design, part number (P/N) 70975-1.

The FAA's Determination

    After examining the circumstances and reviewing all available 
information related to the incidents described above, including the 
above-referenced service information, the FAA has determined that AD 
action should be taken to prevent interference between the flap pushrod 
and the aileron pushrod caused by the flap actuator overtravel nut 
disengaging, which could result in loss of aileron control.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other Air Tractor Models AT-300, AT-301, AT-302, 
AT-400, AT-400A, AT-401, AT-401A, AT-401B, AT-402, AT-402A, AT-402B, 
AT-501, AT-502, AT-502A, AT-502B, and AT-503A airplanes of the same 
type design, the FAA is proposing AD action to supersede AD 96-23-19. 
The proposed AD would require replacing the existing flap actuator 
overtravel stop

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with a new one of improved design, P/N 70975-1. Accomplishment of the 
proposed replacement would be required in accordance with Snow 
Engineering Co. Service Letter #165, dated May 15, 1998.

Cost Impact

    The FAA estimates that 1,250 airplanes in the U.S. registry would 
be affected by the proposed AD, that it would take approximately 2 
workhours per airplane to accomplish the proposed replacement, and that 
the average labor rate is approximately $60 an hour. The manufacturer 
will supply parts at no cost to the owners/operators of the affected 
airplanes. Based on these figures, the total cost impact of the 
proposed AD on U.S. operators is estimated to be $150,000, or $120 per 
airplane.

Regulatory Impact

    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 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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Airworthiness Directive 
(AD) 96-23-19, Amendment 39-9823 (61 FR 58985, November 11, 1996), and 
by adding a new AD to read as follows:

Air Tractor, Inc.: Docket No. 98-CE-62-AD; Supersedes AD 96-23-19, 
Amendment 39-9823.
    Applicability: The following model and serial numbered 
airplanes, certificated in any category, that do not have a part 
number (P/N) 70975-1 flap actuator overtravel stop installed:
    Models AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-401A, 
AT-401B, AT-402, AT-402A, and AT-402B airplanes, serial numbers 300-
0001through 401B-1013; and
    Models AT-501, AT-502, AT-502A, AT-502B, and AT-503A airplanes, 
serial numbers 502-0001 through 502B-0398.

    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 (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 within the next 50 hours time-in-service 
(TIS) after the effective date of this AD, unless already 
accomplished.
    To prevent interference between the flap pushrod and the aileron 
pushrod caused by the flap actuator overtravel nut disengaging, 
which could result in loss of aileron control, accomplish the 
following:
    (a) Install a new flap actuator overtravel stop with a new one 
of improved design, P/N 70975-1. Accomplish this replacement in 
accordance with the REWORK INSTRUCTIONS section of Snow Engineering 
Co. Service Letter #165, dated May 15, 1998.
    (b) Special flight permits may be issued in accordance with 
sections 21.197 and 21.197 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.
    (c) An alternative method of compliance or adjustment of the 
compliance times that provides an equivalent level of safety may be 
approved by the Manager, Fort Worth Airplane Certification Office 
(ACO), 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150.
    (1) The request shall be forwarded through an appropriate FAA 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Fort Worth ACO.
    (2) Alternative methods of compliance approved in accordance 
with AD 96-23-19 are not considered approved as alternative methods 
of compliance for this AD.

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

    (d) All persons affected by this directive may obtain copies of 
the documents referred to herein upon request from Air Tractor Inc., 
P. O. Box 485, Olney, Texas 76374; or may examine these documents at 
the FAA, Central Region, Office of the Regional Counsel, Room 1558, 
601 E. 12th Street, Kansas City, Missouri 64106.
    (e) This amendment supersedes AD 96-23-19, amendment 39-9823.

    Issued in Kansas City, Missouri, on July 14, 1998.
Marvin R. Nuss,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-19327 Filed 7-20-98; 8:45 am]
BILLING CODE 4910-13-P