October 4, 1999

Robert E. Scoville Jr.
P.O. Box 347
Smyrna, TN 37167

Ref: 17274599

Dear Mr. Scoville,

Thank you for requesting our assistance concerning fuel contamination, specifically water in the aircraft wing fuel tanks.

As you are well aware fuel contamination is an ongoing concern of all parties in aviation (pilots, mechanics/maintenance facilities, fueling operations/suppliers, FAA & OEM"s). A clean contamination free fuel source is paramount in safe aircraft operation.

Integral wing fuel tank design was introduced for the 100 series strut braced aircraft beginning in 1979. This design enhanced fuel quantity and crash-worthiness and has a proven service record in the many aircraft delivered with integral fuel tanks.

Certification testing of the integral fuel tank has demonstrated the original fuel drain (1 each per wing) to sufficiently allow detection of contaminants with the airplane at a level normal ground attitude.
In 1992 service bulletin SEB92-25, "Additional Fuel Tank Drain Installation" was released announcing service kits for installation of additional drains. These additional drains allowed checking for fuel contamination at various aircraft attitudes other than the desired level normal ground condition.

Additionally, your aircraft has fuel sampling drains located at the fuel selector valve and fuel strainer.

When during aircraft pre-flight inspection that an excessive amount of fuel system drain sampling is required for a completely clear sample, fuel contamination would then be suspected. A mandatory complete de-fuel and cleaning of the fuel system shall be required prior to flight.

Cessna Aircraft Company P.O. Box 7706, Wichita, Kansas 67277, 316-517-5800 Fax 316-942-9006

The fuel tank drains should be utilized to de-fuel the aircraft.
If during this cleaning/inspection of the fuel system that any large pockets of fluid remaining in the tanks are discovered these retention areas must be identified and a cause determined i.e. sealant blocking "weep holes", etc. and appropriate maintenance action taken to disposition noted discrepancies. Inspection of the fuel cap Adapters/plates and seals/sealing surfaces and dispositioning any discrepancies will assist in prevention of contamination entry.

Fuel supplies/suppliers that are utilized to service the airplane containing suspected contamination must be thoroughly investigated, cause identified and eliminated, suspect fuel should never be allowed in the airplane.

In summary the integral fuel tank design is well proven in many safe daily aircraft operations throughout the world and I am confident that when all the aforementioned items are reviewed that your Skyhawk will give you many enjoyable flights.

Mr. Scoville, I hope this information is helpful and please do not hesitate to contact me if I can assist further on this matter or any other concern you may have.

Sincerely,

Steve Brooks
Manager,
Technical Information Services

Cessna Aircraft Company P.O. Box 7706, Wichita, Kansas 67277, 316-517-5800 Fax 316-942-9006