AD 97-13-11

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 97-13-11, which was sent previously to known U.S. owners and operators of certain Ayres Corporation (Ayres) S2R series airplanes. This AD requires inspecting the 1/4-inch and 5/16-inch bolt hole areas on the lower spar caps for fatigue cracking, and replacing any lower spar cap if fatigue cracking is found. This AD results from an accident on an Ayres S2R series airplane where the wing separated from the airplane in flight. The actions specified by this AD are intended to prevent fatigue cracking of the lower spar caps, which, if not detected and corrected, could result in the wing separating from the airplane with consequent loss of control of the airplane.

Final rule; request for comments.

97-13-11 AYRES CORPORATION: Amendment 39-10071; Docket No. 97-CE-44-AD.
Applicability: Airplanes with the following model and serial number designations with or without a -DC suffix, certificated in any category:

Group 1 Airplanes

Model
Serial Numbers
S-2R
5000R through 5099R.

S2R-R1340
R1340-011, R1340-012, R1340-019, R1340-020,
R1340-024, R1340-025, and R1340-027.

S2R-R1820
R1820-001 through 1820-035.

S2R-T34
6000R through 6049R, T34-001 through T34-143,
T34-145, T34-147 through T34-167, T34-171, T34-180, and T34-181*.
S2R-T15
T15-001 through T15-033**.
S2R-T11
T11-001 through T11-005.
S2R-G1
G1-101 through G1-108.

* The serial numbers of the Model S2R-T34 airplanes could incorporate T34-xxx, T36-xxx, T41-xxx, or T42-xxx. This AD applies to all of these serial number designations as they are all Model S2R-T34 airplanes.

** The serial numbers of the Model S2R-T15 airplanes could incorporate T15-xx and T27-xx. This AD appliesto both of these serial number designations as they are both Model S2R-T15 airplanes.

Group 2 Airplanes

Model
Serial Numbers
S2R-R1340
R1340-028 through R1340-035.
S2R-R1820
R1820-036.
S2R-T65
T65-001 through T65-017.
S2RHG-T65
T65-002 through T65-017.

S2R-T34
T-34-144, T34-146, T34-168, T34-169, T34-172 through T34-179, and T34-189 through T34-226*.
S2R-T45
T45-001 through T45-014.
S2R-G6
G6-101 through G6-146.
S2R-G10
G10-101 through G10-138.
S2R-G5
G5-101 through G5-105.

* The serial numbers of the Model S2R-T34 airplanes could incorporate T34-xxx, T36-xxx, T41-xxx, or T42-xxx. This AD applies to all of these serial number designations as they are all Model S2R-T34 airplanes.

Group 3 Airplanes*

600 S2D
All serial numbers beginning with 600-1311D.
S-2R
1380R and 1416R through 4999R.

S2R-1340R
R1340-001 through R1340-010, R1340-013 through R1340-018, R1340-021 through R1340-023, and R1340-026.
S2R-R3S
R3S-001 through R3S-011

*Any Group 3 airplane that has been modified with a hopper of a capacity over 400 gallons, a piston engine greater than 600 horsepower, or any gas turbine engine makes the airplane a Group 1 airplane for the purposes of this AD. The owner/operator must inspect the airplane at the Group 1 compliance time specified in the Compliance section of this AD.

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 (e) 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: Inspections required as indicated below and any necessary replacement required prior to further flight as indicated in the body of this AD, except to those operators receiving this:

- Group 1 Airplanes: Required initially upon the accumulation of 2,700 hours time-in-service (TIS) on each lower spar cap or prior to further flight after the effective date of this priority letter AD, whichever occurs later, except to those operators receiving this action by priority letter issued June 6, 1997, which made the inspection effective prior to further flight after receipt of the priority letter on airplanes with 2,700 hours TIS or more.

- Group 2 Airplanes: Required initially upon the accumulation of 4,300 hours TIS on each lower spar cap or prior to further flight after the effective date of this AD receipt of this priority letter AD, whichever occurs later, except to thoseoperators receiving this action by priority letter issued June 6, 1997, which made the inspection effective prior to further flight after receipt of the priority letter on airplanes with 4,300 hours TIS or more.

- Group 3 Airplanes: Required initially upon the accumulation of 9,000 hours TIS on each lower spar cap or prior to further flight after receipt of this priority letter AD, whichever occurs later, except to those operators receiving this action by priority letter issued June 6, 1997, which made the inspection effective prior to further flight after receipt of the priority letter on airplanes with 9,000 hours TIS or more.

To prevent fatigue cracking of the lower spar caps, which, if not detected and corrected, could result in the wing separating from the airplane with consequent loss of control of the airplane, accomplish the following:

(a) Inspect, using magnetic particle procedures, the 1/4-inch and 5/16-inch bolt hole areas on each lower spar cap for fatigue cracking. Accomplishment of the inspection is in accordance with Ayres Service Bulletin No. SB-AG-39, dated September 17, 1996.

(1) The magnetic particle inspection must follow American Society for Testing Materials (ASTM) E1444-94A, using wet particles meeting the requirements of the Society for Automotive Engineers (SAE) AMS 3046.

(2) This inspection is to be accomplished by a Level 2 or Level 3 inspector certified using the guidelines established by the American Society for Nondestructive Testing or MIL-STD-410.

(b) If any cracking is found during the inspection required by this AD, prior to further flight, replace the affected lower spar cap in accordance with the affected maintenance manual. Upon replacement, total hours TIS starts over for that particular lower spar cap. Use the initial compliance time specified in the Compliance section of this AD to determine the next inspection interval.

(c) If cracks are found during any inspection required by this AD, submit a report of inspection findings to the Manager, Atlanta Aircraft Certification Office (ACO), Campus Building, 1701 Columbia Avenue, Suite 2-160, College Park, Georgia 30337-2748; facsimile (404) 305-7348; at the applicable time specified in paragraph (c)(1) or (c)(2) of this AD. The report must include a description of any cracks found, the airplane serial number, and the total number of flight hours on the lower spar cap found cracked. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

(1) For airplanes on which the inspection is accomplished after receipt of this priority letter AD: Submit the report within 10 days after performing the inspection required by paragraph (a) of this AD.

(2) For airplanes on which the inspection has been accomplished prior to the receipt of this priority letter AD: Submit the report within 10 days after receipt of this priority letter AD.

(d) 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 to accomplish the modification requirements of this AD provided the following is followed:

(1) The hopper is empty.

(2) Vne is reduced to 126 miles per hour (109 knots).

(3) Flight into known turbulence is prohibited.

(e) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Atlanta Aircraft Certification Office (ACO), Campus Building, 1701 Columbia Avenue, Suite 2-160, College Park, Georgia 30337-2748. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta ACO.

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

(f) The inspection required by this AD shall be done in accordance with Ayres Service Bulletin No. SB-AG-39, dated September 17, 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 the Ayres Corporation, P.O. Box 3090, One Rockwell Avenue, Albany, Georgia 31706-3090. 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.

(g) This amendment (39-10071) becomes effective on July 23, 1997, to all persons except those persons to whom it was made immediately effective by priority letter AD 97-13-11, issued June 20, 1997, which contained the requirements of this amendment.

Discussion
On June 20, 1997, the FAA issued priority letter AD 97-13-11, which applies to certain Ayres S2R series airplanes. That AD resulted from an accident on an Ayres S2R series airplane where the wing separated from the airplane in flight. Investigation of all resources available to the FAA show nine occurrences of fatigue cracking in the lower spar caps of Ayres S2R airplanes, specifically emanating from the 1/4-inch and 5/16-inch bolt holes. Although the investigation of the above-referenced accident is not complete, the FAA believes that the cause can be attributed to fatigue cracks emanating from the 1/4-inch and 5/16-inch bolt holes in the left lower spar cap.

Data accumulated by the FAA indicates that the fatigue cracks on these Ayres S2R series airplanes become detectable at different times based upon the type of engines and design of the airplane. With this in mind, the FAA has categorized these airplanes into three groups:

- Group 1 airplanes have steel spar caps with aluminum webs. These airplanes are capable of carrying heavier loads and data indicates that inspections in the affected areas of the lower spar cap should begin upon the accumulation of 2,700 hours time-in-service (TIS);

- Group 2 airplanes have steel spar caps with steel webs. Because of the steel webs as opposed to aluminum, data indicates that inspections in the affected areas of the left lower spar cap should begin upon the accumulation of 4,300 hours TIS; and

- Group 3 airplanes, which are the ones manufactured first, have steel spars with aluminum webs and low horsepower radial engines, and thus do not have the ability to carry as much weight as airplanes in the other two groups. Data indicates that inspections in the affected areas of the left lower spar cap should begin upon the accumulation of 9,000 hours TIS.

Manufacture of the affected airplanes began in 1965 with the airplanes incorporating the lower horsepower radial engines. Many of the airplane models referenced in this AD are still currently in production. These airplanes are used in agricultural operations and average 500 hours TIS annually. With this in mind, some of the earlier manufactured airplanes could have as many as 16,000 hours total TIS.

Discussion of the Applicable Service Information
Ayres Service Bulletin No. SB-AG-39, dated September 17, 1996, includes procedures for accomplishing a magnetic particle inspection around the lower spar caps bolt holes. This service bulletin also specifies replacement of any lower spar cap where fatigue cracking is found.

The FAA's Determination and Explanation of the AD
Since an unsafe condition has been identified that is likely to exist or develop in other Ayres S2R series airplanes of the same type design, the FAA issued priority letter AD 97-13-11 to prevent fatigue cracking of the lower spar caps, which, if not detected and corrected, could result in the wing separating fromthe airplane with consequent loss of control of the airplane.

The AD requires inspecting the 1/4-inch and 5/16-inch bolt hole areas on the lower spar caps for fatigue cracking, and replacing any lower spar cap if fatigue cracking is found. Accomplishment of the inspection is in accordance with Ayres Service Bulletin No. SB-AG-39, dated September 17, 1996. This inspection utilizes magnetic particles procedures and must follow American Society for Testing Materials (ASTM) E1444-94A, using wet particles meeting the requirements of the Society for Automotive Engineers (SAE) AMS 3046. This inspection is to be accomplished by a Level 2 or Level 3 inspector certified using the guidelines established by the American Society for Nondestructive Testing or MIL-STD-410.

Determination of the Effective Date of the AD
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on June 20, 1997, to known U.S. operators of certain Ayres S2R series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective as to all persons.

Possible Future Rulemaking
AD 97-13-11 covers all airplanes manufactured as of the date this AD was issued. The manufacturer is currently working on a modification that, if successful, would increase the fatigue life of the lower spar caps on the affected airplanes.

When the modification is complete and based on the FAA s subsequent evaluation of the modification described above, additional rulemaking action may be initiated in the future for the airplanes affected by this AD and airplanes currently being manufactured.

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 rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 97-CE-44-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 FAAhas 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. A copy of it, if filed, 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 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.

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