SumpThis: Fuel Contamination in General Aviation Aircraft

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20 June 1985

An open letter to:

1. The Chairman, National Transportation Safety Board

2. The Administrator, Federal Aviation Administration

Within the past several years our attention has been focused on unexplained engine failures in general aviation aircraft accidents. In researching some of these accidents, certain differences and similarities began to emerge. Some of the similarities now clearly indicate that water ingestion through the regular fuel system was the cause of many engine failures. This was surprising since the CAR's and FAR's under which these aircraft were certified provide for the positive removal of water from the fuel system before flight. Obviously, something is wrong.

A series of tests on some of these fuel systems was undertaken. Aircraft were tested in the field under real world conditions to determine how much water would be retained in the tanks after compliance with the manufacturers recommended methods of draining the system before flight. To date no aircraft has met the requirements of the regulations for fuel system design. All aircraft tested fail to meet the drain requirements of CAR 3.553, CAR 3.444 (c), FAR 23.971 (b), or FAR 23.999. Some fail to meet the venting, draining of compartments, and isolation requirements as well.

Aircraft tested to date are:

Cessna 177
Cessna 206
Cessna U206
Cessna T207

Cessna 182
PA-24-250
PA-23-150

In all cases excess water was retained in the tanks after intentional introduction of water into the tanks through the regular filler neck. The water was dyed for easier sighting and positive collection before introduction. In one case, as much as a gallon of water remained in the aircraft tanks after compliance with the Owner's Manual procedures for pre-flight. In all cases extraordinary methods for removal did not find and purge all the water from the systems.

Several 210 aircraft of varying vintages have been examined, post crash, and were found to have had water in excess amounts in the fuel system prior to the crash. This applies to those aircraft with integral tanks as well as those equipped with bladder tanks.

Further field testing of general aviation aircraft for water retention is planned. Past tests were recorded on TV tape and are available if desired. All future tests will also be adequately recorded to properly document this work.

As a result of these tests and the continued loss of life in unexplained aircraft accidents in general aviation, it is recommended that a one time water retention test be conducted on all general aviation aircraft and that those failing to meet the requirements of current or past regulations under which they were certified be grounded until those requirements can be met by demonstration.

It is recognized that this recommendation is harsh in that many aircraft may not meet the requirements. However, engine failures, many unexplained, are the greatest cause of fatal accidents in the Cessna 210 series of aircraft. The same may prove true of other types if a thorough analysis of all fatal accidents was undertaken.

In the past, techniques for determining water contamination as the cause of engine stoppage were yet to be refined. Today those techniques are available and should be used in all investigations where otherwise unexplained power loss or engine stoppage occurs.

Research is underway to demonstrate the effects of water in reciprocating engines so that good investigative procedures may be employed in the future. Current information concerning water ingestion will gladly be shared with both the NTSB and the FAA if desired. Assistance in further refining these investigative techniques would be welcomed.

In the interest of saving life and property, and improving the safety of general aviation, it is again recommended that proof of proper certification be demonstrated in-so-far as fuel systems are concerned in all general aviation aircraft. Proof should consist of a demonstrated ability to find and eliminate all water in the fuel system by reasonable pre-flight procedures performed by pilots…..not mechanics.

The courtesy of a reply concerning the intentions of both the NTSB and the FAA in this regard is requested. Such a reply will certainly aid in the planning and execution of future tests and research.

Respectfully,

Norman L. Horton

Jerry L. Wells

Home Documents Images Message Board
(Use your browser's back button to return to the page that you were previously viewing.)

	20 June 1985
	An open letter to:

	1. The Chairman, National Transportation Safety Board
	2. The Administrator, Federal Aviation Administration

	Within the past several years our attention has been focused on unexplained engine failures in general aviation aircraft accidents. In researching some of these accidents, certain differences and similarities began to emerge. Some of the similarities now clearly indicate that water ingestion through the regular fuel system was the cause of many engine failures. This was surprising since the CAR's and FAR's under which these aircraft were certified provide for the positive removal of water from the fuel system before flight. Obviously, something is wrong.

	A series of tests on some of these fuel systems was undertaken. Aircraft were tested in the field under real world conditions to determine how much water would be retained in the tanks after compliance with the manufacturers recommended methods of draining the system before flight. To date no aircraft has met the requirements of the regulations for fuel system design. All aircraft tested fail to meet the drain requirements of CAR 3.553, CAR 3.444 (c), FAR 23.971 (b), or FAR 23.999. Some fail to meet the venting, draining of compartments, and isolation requirements as well.

	Aircraft tested to date are:

	In all cases excess water was retained in the tanks after intentional introduction of water into the tanks through the regular filler neck. The water was dyed for easier sighting and positive collection before introduction. In one case, as much as a gallon of water remained in the aircraft tanks after compliance with the Owner's Manual procedures for pre-flight. In all cases extraordinary methods for removal did not find and purge all the water from the systems.

	Several 210 aircraft of varying vintages have been examined, post crash, and were found to have had water in excess amounts in the fuel system prior to the crash. This applies to those aircraft with integral tanks as well as those equipped with bladder tanks.

	Further field testing of general aviation aircraft for water retention is planned. Past tests were recorded on TV tape and are available if desired. All future tests will also be adequately recorded to properly document this work.

	As a result of these tests and the continued loss of life in unexplained aircraft accidents in general aviation, it is recommended that a one time water retention test be conducted on all general aviation aircraft and that those failing to meet the requirements of current or past regulations under which they were certified be grounded until those requirements can be met by demonstration.

	It is recognized that this recommendation is harsh in that many aircraft may not meet the requirements. However, engine failures, many unexplained, are the greatest cause of fatal accidents in the Cessna 210 series of aircraft. The same may prove true of other types if a thorough analysis of all fatal accidents was undertaken.

	In the past, techniques for determining water contamination as the cause of engine stoppage were yet to be refined. Today those techniques are available and should be used in all investigations where otherwise unexplained power loss or engine stoppage occurs.

	Research is underway to demonstrate the effects of water in reciprocating engines so that good investigative procedures may be employed in the future. Current information concerning water ingestion will gladly be shared with both the NTSB and the FAA if desired. Assistance in further refining these investigative techniques would be welcomed.

	In the interest of saving life and property, and improving the safety of general aviation, it is again recommended that proof of proper certification be demonstrated in-so-far as fuel systems are concerned in all general aviation aircraft. Proof should consist of a demonstrated ability to find and eliminate all water in the fuel system by reasonable pre-flight procedures performed by pilots…..not mechanics.

	The courtesy of a reply concerning the intentions of both the NTSB and the FAA in this regard is requested. Such a reply will certainly aid in the planning and execution of future tests and research.