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National Transportation Safety Board
Washington, D.C. 20594

August 3, 1987

Mr. Norman L. Horton
Mr. Jerry L. Wells
Aviation Safety and Management Consultants
4582 Old Stage Road
Central Point, Oregon 97502

 

Dear Messrs. Horton and Wells:

 

Thank you for your letter of June 11, 1987, regarding potential engine failure due to water contamination in the fuel systems of Piper Model PA-23 airplanes.

 

I discussed the subject of water in the fuel of general aviation airplanes in my letter to you of September 20, 1985, and referred to a number of related safety recommendations which the National Transportation Safety Board had issued to the Federal Aviation Administration (FAA). At that time, the Safety Board was in the process of evaluating the fuel preflight and drainage provisions of Piper Apache Models PA-23-150, -160, and -235. Subsequently, on October 16, 1985, the Safety Board issued Safety Recommendations A-85-77 through -80 to the FAA relating to water/ice in the fuel systems of these airplanes (copy enclosed), The recommendations addressed the need for installation of individual fuel line drain valves; supplemental service and operating information describing preflight fuel sampling procedures; and the use of fuel additives in cold weather operations.

 

The FAA, in their January 14, 1986, response to these recommendations, told the Safety Board that their Small Airplane Certification Directorate had completed a review of the design of the PA-23 fuel system and found that it complied with Civil Air Regulation (CAR) 3, Subparts 3.444 and 3.553. As a result, they did not believe that it was necessary to require the installation of additional fuel line drain valves in these airplanes. However, they did concur with the other aspects of the recommendations and several remedial actions were accomplished. For example, the Piper Aircraft Corporation issued Service Bulletin No. 827, "Fuel System Draining Procedure-Water Contamination," Applicable to PA-23-150 and -160 Models, and the FAA published a special issue of Advisory Circular (AC) 43-16, General Aviation Airworthiness Alerts, entitled "Winter Operations".

 

The information contained in your letter regarding possible contamination due to water entrapment in the fuel systems of Piper PA-23 airplanes conflicts with the aforementioned conclusions reached by the FAA. That is, Subpart 3.44 (c) of CAR 3 requires that "when the airplane is in the normal ground attitude, water will drain from all portions of the tanks to the sediment bowl". As you know, the Safety Board is primarily an investigative agency and, unlike the FAA, has no direct authority regarding aircraft certification, nor do we have the resources to conduct or oversee extensive certification testing. Nonetheless, we are concerned about the potential hazard of water entrapment in general aviation aircraft. Consequently, I have asked our technical staff to review the design of the PA-23 fuel system and the fuel system test results (VHS Video Film "PA-23, No. 1") submitted with your letter in an effort to determine whether any additional action is required by the Safety Board. I will provide you with a further advisory when our evaluation of this matter has been completed

 

The Safety Boars is appreciative of your efforts to improve general aviation fuel system safety.

Respectfully yours,

Jim Burnett
Chairman

Enclosure

 

 

 

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