Airworthiness Directive

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Federal Aviation Administration

14 CFR Part 39

Docket No. 93-CE-32-AD; Amendment 39-8749; AD 93-23-13

Airworthiness Directive; PIPER AIRCRAFT CORPORATION Model PA-31, PA-31-300, PA-31-325 and PA-31-350 Airplanes
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93-23-13 PIPER AIRCRAFT CORPORATION: Amendment 39-8749. Docket No. 93-CE- 32-AD. Supersedes AD 93-02-13, Amendment 39-8496 which superseded AD 92-26-02, Amendment 39-8429 and AD 80-20-04, Amendment 39-3925.

Applicability: Model PA31, PA31-300, and PA31-325 airplanes (serial numbers 31-2 through 31-8012089), and Model PA31-350 airplanes (serial numbers 31-5001 through 31-8052199), certificated in any category.

Compliance: Required initially within the next 50 hours time-in-service (TIS) after the effective date of this AD, unless already accomplished (compliance with AD 80-20-04, Amendment 39-3925, AD 92-26-02, Amendment 39-8429, or AD 93-02-13, Amendment 39- 8496), and thereafter as indicated.

To prevent improper sealing of the baffle seals to the engine cowling, which could result in high engine operating temperatures, accomplish the following:

(a) Visually inspect the engine baffle seals for proper positioning by using a light and looking in air inlets and access doors to ensure that forward seals and lower aft seals are all facing forward and not blown back.

(b) If baffle seals are improperly positioned (blown back), prior to further flight, accomplish one of the following:

(1) Install thicker baffle seals in accordance the instructions to Piper Kit 764 093, dated November 10, 1980; or

NOTE 1: Piper Kit 764 093 includes the entire baffle assembly consisting of both baffles and baffle seals. Replacing the baffle seals included in this kit is the only requirement of paragraph (b)(1) or (c)(2) of this AD.

(2) Install baffles of one of the following materials in accordance with Figure 1 of this AD:

(i) Brown Aircraft Supply Engine Baffle Material, part number (P/N) BA71646-1 and BA71646-2, temperature range -40 to 300 degrees Fahrenheit.

(ii) Brown Aircraft Supply, Fiber Reinforced High Temperature Silicone Engine Baffle Material (red), P/N T-95182, temperature range -65 to 550 degrees Fahrenheit; and

(iii) Brown Aircraft Supply, Engine Baffle Material, P/N T-8071, temperature range -40 to 300 degrees Fahrenheit.


1. Inspect the existing baffle seals through the front of the cowl to ensure existing seals are of sufficient length to provide at least 1-inch of contact with upper and lower cowls when properly positioned. Mark areas that need lengthening, and note the minimum length needed to meet requirements.

2. Remove the cowls in accordance with the applicable maintenance manual. Remove rivets, wire, and screws, as applicable, that secure baffle seals (fabric) to the engine baffles (metal). Retain any metal strips that are used to secure seals to the engine baffles.

3. Remove existing baffle seals and lay against Brown Aircraft Supply baffle seal material.

4. Cut new seals around the layout, ensuring that seals are lengthened as noted in procedure 1.

5. Reattach new seals to the engine baffles with the original screws, rivets, and wires, as applicable, or new hardware of the same part number.

NOTE: The front upper cowl baffle seal is most critical, especially at the inboard and outboard corners. If the old material can be removed intact, and the curve can be transferred to the new flat material, then it may not be necessary to slit the material where it curves from vertical to horizontal contact with the cowl. If the curve requires a slit in the material at the corner, then it is recommended that the slit be tied with ty-raps or safety wire to ensure contact with the cowl around the radius.

(c) If baffle seals are properly positioned (not blown back), within the next 50 hours TIS, accomplish one of the following:

(1) Reinspect the engine baffle seals as specified in paragraph (a) of this AD, and continue to reinspect thereafter at intervals not to exceed 50 hours TIS; or

(2) Install thicker baffle seals as specified in either paragraph (b)(1) or (b)(2) of this AD. This installation terminates the inspection requirements of this AD.

(d) The inspections required by this AD may be performed by the owner/operator holding at least a private pilot certificate as authorized by FAR 43.7, and must be entered into the aircraft records showing compliance with this AD in accordance with FAR 43.11.

(e) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(f) 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, Atlanta Aircraft Certification Office, 1669 Phoenix Parkway, Suite 210C, Atlanta, Georgia 30349. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta Aircraft Certification Office.

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

(g) The installation (using Piper Aircraft Corporation parts) required by this AD shall be done in accordance with Piper Kit 764 093, dated November 11, 1980. 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 Piper Aircraft Corporation, 2926 Piper Drive, Vero Beach, Florida 32960. 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.

(h) This amendment (39-8749) supersedes AD 93-02-13, Amendment 39-8496 which superseded AD 92-26-02, Amendment 39-8429 and AD 80-20-04, Amendment 39-3925.

(i) This amendment becomes effective on January 21, 1994.

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