AD 96-10-12

This amendment adopts a new airworthiness directive (AD) that applies to Aviat Aircraft, Inc. (Aviat) Models S-1S, S-1T, S-2, S-2A, S-2S, and S-2B airplanes that are equipped with a flight control stick with a wall thickness of .035 inch. This action requires repetitively inspecting the flight control stick for cracks, and replacing any cracked flight control stick with one with a wall thickness of .058 inch. An incident on an Aviat Model S-2A airplane where the flight control stick fractured in flight prompted this action. The actions specified by this AD are intended to prevent the inability to maneuver the airplane because of a cracked flight control stick, which, if not detected and corrected, could result in loss of control of the airplane.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of June 7, 1996.

Comments for inclusion in the Rules Docket must be received on or before July 19, 1996.

Final rule; request for comments.

96-10-12 AVIAT AIRCRAFT, INC.: Amendment 39-9619; Docket No. 96-CE-20-AD.

Applicability: Models S-1S, S-1T, S-2, S-2A, S-2S, and S-2B airplanes (formerly known as Pitts Models S-1S, S-1T, S-2, S-2A, S-2S, and S-2B airplanes), all serial numbers, certificated in any category, that are equipped with a flight control stick with a wall thickness of .035 inch.

NOTE 1: All Model S-2A airplanes and some Model S-2S airplanes were equipped with a .035-inch wall thickness flight control stick at manufacture. Models S-1S, S-1T, S-2, S-2B and certain Model S-2S airplanes were manufactured with control sticks with a wall thickness greater than .035 inch, but could have .035-inch flight control sticks installed through FAA-approved field modification.

NOTE 2: 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 initially upon accumulating 1,000 hours time-in-service (TIS) or within the next 25 hours TIS after the effective date of this AD, whichever occurs later, unless already accomplished, and thereafter as indicated in the body of this AD.

To prevent the inability to maneuver the airplane because of a cracked control stick, which, if not detected and corrected, could result in loss of control of the airplane, accomplish the following:

(a) Inspect, using dye penetrant methods, the .035-inch wall thickness flight control stick for cracking in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Aviat Service Bulletin (SB) No. 23, dated March 29, 1996.

NOTE 3: Aviat SB No. 23, dated March 29, 1996, only references the Model S-2A airplanes. The procedures included in this service bulletin should be utilized for all of the airplanes affected by this AD.

(1) If cracking is found, prior to further flight, replace the .035-inch wall thickness flight control stick with one with a .058 inch wall thickness in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Aviat SB No. 23, dated March 29, 1996.

(2) If no cracks are found, reinspect at intervals not to exceed 50 hours TIS. If cracking is found during any repetitive inspection, prior to further flight, accomplish the replacement specified in paragraph (a)(1) of this AD.

(b) Replacing the .035-inch wall thickness flight control stick with one with a .058-inch wall thickness in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Aviat SB No. 23, dated March 29, 1996, is considered terminating action for the repetitive inspection requirement of this AD. This replacement may be accomplished at any time, and must be accomplished prior to further flight if cracking is found as required by paragraph (a)(1) of this AD.

(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, Denver Aircraft Certification Office, 5440 Roslyn Street, suite 133, Denver, Colorado 80216. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Denver ACO.

NOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Denver ACO.

(e) The inspection and replacement (if necessary) required by this AD shall be done in accordance with Aviat Service Bulletin No. 23, dated March 29, 1996. 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 Aviat Aircraft, Inc., The Airport-Box 1240, South Washington Street, Afton, Wyoming 83110. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on June 7, 1996.

Events Leading to This Action

The FAA has received a report of the flight control stick fracturing in flight on an Aviat Model S-2A airplane. Analysis of the fractured flight control stick revealed fatigue cracking at the upper weld above the pivot bearing. The flight control stick in the referenced incident had a wall thickness of .035-inch. If not detected and corrected, a cracked flight control stick could result in the inability to maneuver the airplane with subsequent loss of control of the airplane.

Aviat has issued Service Bulletin (SB) No. 23, dated March 29, 1996, which specifies procedures for (1) inspecting, using dye penetrant methods, the .035-inch wall thickness flight control stick; and (2) installing a flight control stick with a wall thickness of .058 inch.

The affected airplane had accumulated 2,015 hours time-in-service (TIS) when the incident occurred. The FAA has determined that cracking in this area can develop after 1,000 hours TIS accumulated on a .035-inch wall thickness flight control stick. All Model S-2A airplanes and some Model S-2S airplanes were equipped with a .035-inch wall thickness flight control stick at manufacture. Models S-1S, S-1T, S-2, S-2B and certain Model S-2S airplanes were manufactured with control sticks with a wall thickness greater than .035 inch, but could have .035-inch flight control sticks installed through FAA-approved field modification.

After examining the circumstances and reviewing all available information related to the incident described above, the FAA has determined that (1) flight control sticks with a wall thickness of .035 inch should be repetitively inspected for cracking after 1,000 hours TIS; and (2) AD action should be taken to prevent the inability to maneuver the airplane because of a cracked flight control stick, which, if not detected and corrected, could result in loss of control of the airplane. Explanation of the Provisions of the ADSince an unsafe condition has been identified that is likely to exist or develop in other Aviat S- 1S, S-1T, S-2, S-2A, S-2S, and S-2B airplanes of the same type design that are equipped with a .035-inch wall thickness flight control stick, this AD requires repetitively inspecting the affected flight control stick for cracks, and replacing any cracked flight control stick with one with a wall thickness of .058 inch. This action also allows the option of installing a .058-inch wall thickness flight control stick as terminating action for the repetitive inspection requirement if cracks were not found. Accomplishment of the required actions are in accordance with Aviat SB No. 23, dated March 29, 1996.

Since a situation exists (possible inability to maneuver the airplane with subsequent loss of control of the airplane) that requires the immediate adoption of this regulation, it is found that notice and opportunity for public prior comment hereon are impracticable, and that goodcause exists for making this amendment effective in less than 30 days. Comments Invited

Although this action is in the form of a final rule that involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to comment, comments are invited on this rule. Interested persons are invited to comment on this 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 will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic,environmental, and energy aspects of the rule that might suggest a need to modify the 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 AD 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. 96-CE-20-AD." The postcard will be date stamped and returned to the commenter. Regulatory Impact

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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a significant regulatory action under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the AmendmentAccordingly, 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 USC 106(g), 40113, 44701.

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