Memorandum

Date: July 23, 1999

To: Frank Del Gandio, Jeff Gorney, AAI-200

From: Craig Roberts, A.S.I. Nashville FSDO

Subject: Water Entrapment in Integral Wing Tanks of N52749

Mr. Robert Scovill is the owner of a Cessna CE-172P, serial number 17274599, registration number N52749, which he purchased new in 1981. Mr. Scovill came to this office with a concern about a concerning problem with this aircraft. Over the last 2 years he has experienced 1 incident of a rough running while on approach to MBT (Murfreesboro Municipal Airport, Murfreesboro, TN) and 3 separate in-flight shutdowns which resulted in forced landings at MBT, a field in Shelbyville, TN and at MQY (Smyrna, TN) respectively (see attached letter submitted by Robert Scovill, page 3, 'History'). Mr. Scovill had stated to me that he had always flown the aircraft without any abrupt maneuvers until prior to the engine problems when he began to practice steep bank turns, turns about a point, etc.

Per Mr. Scovill's request, myself and FAA Inspector Paul Jones attended an experiment on his aircraft involving the introduction of dyed water into the left wing fuel tank through the opened wing panels (3) and fuel filler port by Mr. Scovill and Bill Allen, Facilities Manager, Middle Tennessee State University Aerospace Dept. (see attached report by Bill Allen). The test was held in the hangar of MTSU. A second test was also held at the same facility on July 12, 1999 again utilizing the left wing. This test was attended by myself, Bill Allen and Mr. Scovill. Mr. Allen and Mr. Scovill introduced dyed water into the left wing fuel tank in areas forward of each hat channel on both side of both ribs. As water overflowed each area (i.e. rib to hat channel intersection) and migrated to the original fuel sump, this water was sumped and reintroduce into another area of the tank. This process was repeated until a total of 32 ounces of water was introduced into the wing tank and no water was removed via a sump sample. After allowing the tank to settle for approximately 1 hour, 6 ounces of water was removed from the sump. The wings were shook for 30 seconds and an additional 13 ounces of water was removed. Subsequent sump samples resulted in no water removal. A total of 13 ounces of water remained entrapped within the left wing fuel tank.

Please note that following the forced landing in the field near Shelbyville, TN, Mr. Scovill contacted Cessna and was informed of Service Kit SK182-100 which adds 4 fuel drains to each wing tank. Mr. Scovill decided to have his mechanic install the additional drains. In both of the tests described above, water was never removed from any of the additional 4 fuel drains installed. Cessna Service Bulletin SEB92-25 covers this kit and is categorized as mandatory compliance.

Recommendation:

1.

A review of the water/contamination egress capability of the Cessna integral fuel tank which include all similar designs to the CE-172P model.

2.

Review the effectiveness of Service Kit SK182-100