AD 96-15-02

This amendment adopts a new airworthiness directive (AD) that is applicable to Pratt & Whitney Wasp series and R-1340 series (military) reciprocating engines. This action requires initial and repetitive visual and dye penetrant inspections of the crankshaft counterweights for cracks, and replacement of cracked crankshaft counterweights with improved crankshaft counterweights. This amendment is prompted by reports of crankshaft counterweight cracking. The actions specified in this AD are intended to prevent engine failure due to crankshaft counterweight failure, which could result in damage to or loss of the aircraft.

Final rule; request for comments.

96-15-02 Pratt & Whitney: Amendment 39-9693. Docket 95-ANE-26.
Applicability: Pratt & Whitney (PW) Wasp Models S1H1 and S3H1, and Model R-1340-AN-1 (military) reciprocating engines, incorporating Air Tractor, Inc. Parts Manufacturer Approval (PMA) crankshafts, Part Number (P/N) 90114. These engines are installed on but not limited to the following aircraft: Ag Cat Corporation (formerly Schweizer Aircraft Corporation) Models G-164A, G-164B, and G-164C; Air Tractor, Inc. Models AT-301 and AT-401; Ayres Corporation Models 600 S-2C, 600 S2D, S-2R, S2R-R1340; EMAIR Model MA-1; North American Aviation, Inc. Models BC-1A, AT-6, AT-6A, AT-6B, AT-6C, AT-6D, AT-6F, and T-6G; and Transland Model Ag-2.
NOTE: This airworthiness directive (AD) applies to each engine 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 engines 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 (h) 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 as indicated, unless accomplished previously.
To prevent engine failure due to crankshaft counterweight failure, which could result in damage to or loss of the aircraft, accomplish the following:
(a) For crankshafts with 290 or more hours time in service (TIS) on the effective date of this AD, perform an initial visual and dye penetrant inspection of the crankshaft counterweights for cracks within 10 hours TIS after the effective date of this AD in accordance with Snow Engineering Co. Service Letter (SL) No. 135, dated February 1, 1995. If cracks are found, prior to further flight, remove from service and rework the crankshaft by replacing cracked counterweights in accordance with the rework procedures described in Snow Engineering Co. SL No. 134, dated November 29, 1994, or replace with a serviceable part.
(b) For crankshafts with less than 290 hours TIS on the effective date of this AD, perform an initial visual and dye penetrant inspection of the crankshaft counterweights for cracks prior to accumulating 300 hours total TIS on the crankshaft, in accordance with Snow Engineering Co. SL No. 135, dated February 1, 1995. If cracks are found, prior to further flight, remove from service and rework the crankshaft by replacing cracked counterweights in accordance with the rework procedures described in Snow Engineering Co. SL No. 134, dated November 29, 1994, or replace with a serviceable part.
(c) For crankshafts that have not been reworked in accordance with the rework procedures described in Snow Engineering Co. SL No. 134, dated November 29, 1994, perform repetitive visual and dye penetrant inspections of the crankshaft counterweights for cracks, at intervals not to exceed 150 hours TIS since last inspection, in accordance with Snow Engineering Co. SL No. 135, dated February 1, 1995. If cracks are found, prior to further flight remove from service and rework the crankshaft by replacing cracked counterweights in accordance with the rework procedures described in Snow Engineering Co. SL No. 134, dated November 29, 1994, or replace with a serviceable part.
(d) If a cylinder assembly is removed for any reason, perform a visual and dye penetrant inspection of the crankshaft counterweights for cracks in accordance with Snow Engineering Co. SL No. 135, dated February 1, 1995. If cracks are found, prior to further flight, remove from service and rework the crankshaft by replacing cracked counterweights in accordance with the rework procedures described in Snow Engineering Co. SL No. 134, dated November 29, 1994, or replace with a serviceable part. Count the 150 hours TIS interval for the repetitive inspections in accordance with paragraph (c) of this AD at cylinder assembly removal.
(e) At the next overhaul after the effective date of this AD, or at the next crankshaft removal, whichever occurs first, remove from service and replace crankshaft counterweights in accordance with the rework procedures described in Snow Engineering Co. SL No. 134, dated November 29, 1994. Incorporation of the improved crankshaft counterweights, Air Tractor, Inc. P/N 90133-1 and 90134-1, constitutes terminating action to the repetitive inspections required by paragraph (c) of this AD.
(f) No action is required for reworked and new manufactured crankshafts incorporating improved crankshaft counterweights, Air Tractor, Inc. P/N 90133-1 and 90134-1, which are indelibly marked on the counterweight front and rear surfaces.
(g) No action is required for other FAA-approved crankshafts besides those manufactured by Air Tractor, Inc. However, intermixing of Air Tractor, Inc. and other crankshaft assembly parts other than PW crankshaft assembly parts is prohibited. NOTE: Air Tractor, Inc. Top Drawing No. 90U4 permits use of PW components, and virtually all Air Tractor, Inc. crankshafts have some PW parts installed.
(h) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Special Certification Office. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Special Certification Office.
NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Special Certification Office.
(i) Special flight permits may be issued in accordance with sections 21.197and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the inspections can be accomplished.
(j) The actions required by this AD shall be done in accordance with the following service documents:

Document No.
Pages
Date
Snow Engineering Co.
SL No. 134
1-5
November 29, 1994
Total pages: 5.

Snow Engineering Co.
SL No. 135
1-4
February 1, 1995
Total pages: 4.

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 Air Tractor, Inc., Olney Municipal Airport, Olney, TX 76374; telephone (817) 564-5616, fax (817) 564-2348. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(k) This amendmentbecomes effective on August 12, 1996.

The Federal Aviation Administration (FAA) has received reports of counterweight cracking on Air Tractor, Inc., Part Number (P/N) 90114 Parts Manufacturer Approval (PMA) replacement crankshafts installed on Pratt & Whitney (PW) Wasp series and R-1340 series (military) reciprocating engines. Cracks have been found in three rear counterweights, P/N 90134, immediately adjacent to the 4 1/2 order flyweight, or dynamic counterweight. In two cases, the cracks were observed during overhaul inspections after a normal runout; in one case, Air Tractor, Inc. has advised the FAA that a counterweight crack may have caused or contributed to an engine failure during agricultural spraying operations in Argentina. This condition, if not corrected, could result in engine failure due to crankshaft counterweight failure, which could result in damage to or loss of the aircraft.
The manufacturer advised the FAA of the crankshaft counterweight failure in Argentina and the possible connection between this failure and a crack found in a second crankshaft counterweight with 900 hours in agricultural service in the United States. Air Tractor, Inc. released an initial Service Letter (SL), Snow Engineering Co. SL No. 134, dated November 29, 1994, advising all owners of Air Tractor, Inc. PMA crankshafts to perform within the next 10 hours time in service (TIS) a visual and dye penetrant inspection of the crankshaft counterweights to detect cracking. This SL detailed an inspection procedure which required the removal of one cylinder to gain access to the crankshaft. Air Tractor, Inc. demonstrated this inspection procedure to the FAA on November 28, 1994.
In January and February 1995, Air Tractor, Inc. performed an engine test at their facility to demonstrate a reasonable interval for engine operation between inspections. The test consisted of cutting through the counterweight at the location where cracks were initially found and running the engine at a series of loads simulating actual flight loads for 202.5 hours (recording tachometer) without failure. This test was run using an FAA-approved test procedure with FAA oversight.
Based on this experience, Air Tractor, Inc. has issued Snow Engineering Co. SL No. 135, dated February 1, 1995, that supersedes the inspection requirements of Snow Engineering Co. SL No. 134; however, the rework procedure described in Snow Engineering Co. SL No. 134 remains in effect for the purpose of this AD. The FAA has reviewed and approved the technical contents of Snow Engineering Co. SL No. 135, dated February 1, 1995, that describes procedures for an initial inspection of crankshaft counterweights prior to 300 hours TIS, with repetitive inspections every 150 hours TIS. Snow Engineering Co. SL No. 134 describes replacement of crankshaft counterweights, P/N 90133 and 90134, with redesigned FAA-PMA crankshaft counterweights, P/N 90133-1 and 90134-1 at the next overhaul or if a crack is found during an inspection. Air Tractor, Inc. has advised the FAA that it will replace crankshaft counterweights in accordance with Snow Engineering Co. SL No. 134, dated November 29, 1994, on all crankshafts delivered to their facility under warranty, free of charge.
Air Tractor, Inc. has advised the FAA that crankshafts manufactured and shipped after November 18, 1994, incorporate the FAA-approved redesigned crankshaft counterweights, P/N 90133-1 and 90134-1, and are not subject to inspections. Only Air Tractor, Inc. crankshaft counterweights, P/N 90133-1 and 90134-1, are eligible for installation in accordance with the rework procedures described in Snow Engineering Co. SL No. 134. No other parts are currently approved for installation in compliance with this AD.
Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design, this AD is being issued to prevent engine failure due to crankshaft counterweight failure, which could resultin damage to or loss of the aircraft. This AD requires initial and repetitive visual and dye penetrant inspections of the crankshaft counterweights for cracks, and replacement of crankshaft counterweights with improved crankshaft counterweights if a crack is found during inspection, at the next overhaul, or at the next crankshaft removal, whichever occurs first. The actions are required to be accomplished in accordance with the SL described previously.
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause 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 flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment onthis 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 under the caption "ADDRESSES." 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 Number 95-ANE-26." The postcard will be date stamped and returned to the commenter.
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. 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 the following new airworthiness directive: