# AD 79-12-08: Fuel Selector Valves - Type: Airworthiness directive - Status: Current - Products: Piper PA-24-400, PA-30 and PA-39 - Effective: June 19, 1979 - Published: June 14, 1979 - Issued: June 5, 1979 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Amendment: 39-3493 - Registered aircraft: 1,035 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C091A309AC0B84108625699E004AEFF4.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/79-12-08 ## The airworthiness directive 79-12-08 PIPER: Amendment 39-3493. Applies to series PA-24-400 S/N 26-2 through 26-148; PA-30 S/N 30-2 through 30-2000; and PA-39 S/N 39-1 through 39-155 aircraft. PART A This part applies to all aircraft listed above. Compliance required within 50 hours of operation after the effective date of this AD and at each 50 hours of operation thereafter. To prevent fuel mismanagement from inter-port leakage with the fuel selector valve causing fuel to transfer from one tank to another, accomplish checks in accordance with the Instructions paragraph in Piper Service Letter No. 851, Part A or an approved equivalent. Item 3 is to be repeated only twice. If drainage still exceeds one half (1/2) fluid ounce of fuel then comply with Item 5. Item 5 is maintenance and must be performed by a certified mechanic. PART B This part applies to the cited Models PA-30 and PA-39 aircraft. If the airplane has been exposed to below freezing temperatures, compliance is required prior to the first flight of the day and after each refueling operation. To eliminate water contamination of the aircraft fuel supply, accomplish a check in accordance with the Instructions paragraph of Piper Service Letter 851, Part B, Item 2a and 2b or an approved equivalent check. PART C This part applies to the cited Model PA-24-400 aircraft. If the airplane has been exposed to below freezing temperatures, compliance is required prior to the first flight of the day and after each refueling operation. To eliminate water contamination of the aircraft fuel supply, accomplish a check in accordance with the Instructions paragraph in Piper Service Letter No. 851, Part C, Item 2a or an approved equivalent check. Upon submission of substantiating data through an FAA maintenance inspector, the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, may adjust the repetitive intervals. The checks required by this AD may be performed by the pilot. Equivalent checks, inspections, and maintenance must be approved by Chief, Engineering and Manufacturing Branch, FAA, Eastern Region. This amendment is effective June 19, 1979. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A1EA](https://openairdocs.org/tcds/A1EA): Piper Aircraft Inc.; names 2 of 3 models: PA-30, PA-39 - [TCDS 1A15](https://openairdocs.org/tcds/1A15): Piper Aircraft Inc.; names 1 of 4 models: PA-24-400 ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 1,035 (1,035 by airframe model, 0 by engine model) - Makers: Piper 1,035 Models with the most aircraft: - [Piper PA-30](https://openairdocs.org/model/piper-pa-30): 878 aircraft (airframe model) - [Piper PA-39](https://openairdocs.org/model/piper-pa-39): 82 aircraft (airframe model) - [Piper PA-24-400](https://openairdocs.org/model/piper-pa-24-400): 75 aircraft (airframe model) All 3 models: https://openairdocs.org/ad/79-12-08/models.md Every aircraft: https://openairdocs.org/ad/79-12-08/aircraft.md Its text cites no advisory circulars or STCs. ## NTSB investigations that cite this AD (3) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB NYC00LA055](https://openairdocs.org/ntsb/NYC00LA055), Dec 19, 1999: Piper PA-30 (N7397Y), Morristown, NJ, substantial damage. Probable cause: The pilot's failure to obtain proper takeoff airspeed and his failure to follow published emergency procedures. Factors related to the accident were the pilot's inadequate preflight and water… - [NTSB IAD99LA026](https://openairdocs.org/ntsb/IAD99LA026), Jan 5, 1999: Piper PA-30 (N3TH), Fairfield, VA, destroyed. Probable cause: The owner's failure to comply with the Airworthiness Directive and the subsequent fuel system filter blockage by ice leading to fuel starvation and power loss of the right engine. Additionally, the… - [NTSB IAD98FA042](https://openairdocs.org/ntsb/IAD98FA042), Apr 5, 1998: Piper PA-30 (N7845Y), Mcmechen, WV, destroyed, 1 fatal. Probable cause: The pilot's inadequate pre-flight planning and preparation which resulted in fuel exhaustion during takeoff. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.