Airworthiness directives: Air Tractor, Inc.,

[Federal Register: July 21, 1998 (Volume 63, Number 139)]

[Proposed Rules]

[Page 39053-39054]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr21jy98-19]

[[Page 39053]]

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).

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 filedin 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. 98-19327Filed7-20-98; 8:45 am]

   BILLING CODE 4910-13-P