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DATE: May 24, 2000

Investigate Design Flaw in Cessna 172P Aircraft

Control Number: 0064-00
AIR 1 Control Number: 20D01972-0
FAA Safety Recommendations: 99.283 and 99.284
FAA letters to Cessna dated September 23, 1999, and March 13, 2000
Cessna letters L417-02-99-178 dated October 20, 1999 and April 10, 2000

The writer of the e-Mail, Mr. Scovill has taken the position that a design flaw exists in the design of Cessna, high wing, single engine airplanes, equipped with integral wing fuel tanks. His contention is that water in the fuel tanks does not have the ability to reach the wing fuel tank sump area (low point) in the normal ground attitude, and as such cannot be drained and detected prior to flight. Mr. Scovill has experienced four forced landings due to engine stoppage, including one off-airport landing. Mr. Scovill states that regardless of the source of water (i.e.; condensation, fuel load, rain...etc.) the water is not given the opportunity to travel to the single standard equipment fuel tank sump drain valve. His contention is that if there is a hazardous quantity of water in the wing tanks of this type of airplane, the pilot after following all required pre-flight procedures may leave the ground with a hazard quantity of water in the wing fuel tanks. Under this scenario his contention is that this water may find it's way to the fuel tank outlet and hence engine resulting in either power interruptions or engine shutdown due to water contaminated fuel.

The FAA has taken the following action, which is defined in FAA letter to Cessna Aircraft Company (hereafter Cessna) dated March 13, 2000.


We have determined and notified Cessna that an unsafe condition exists on the subject airplanes and that this condition is likely to exist or develop in other airplanes of the same type design.


We have determined and notified Cessna that the design of the subject airplane fuel system and tanks does not comply with the requirements of CAR 3.444 for the subject airplane.


We plan to proceed with Airworthiness Directive action based on the above findings.


We have also determined and notified Cessna that design changes are necessary to correct the unsafe condition. We have requested Cessna submit appropriate design changes for FAA approval within 30 days for the subject airplane.


We have also determined and notified Cessna that this condition may exist on all Cessna high wing integral wing fuel tank equipped airplanes, and have requested Cessna identify all applicable models and serial numbers and submit appropriate design changes for each model for FAA approval within 60 days.


We have notified Cessna of our intent to make a Specific Finding to the requirements of CFR part 23.971 on current Model 182T/T182T programs due to certify in November 2000.


We have requested Cessna perform a full review and submittal of the compliance substantiation for the Model 172, 182 and 206 series airplanes manufactured since the restart of production (Type Certificated since 1996), with respect to the requirements of 14 CFR part 23.971, and water egress capability

Cessna letter to FAA dated April 10, 2000 disagrees with the FAA position after a historical recitation of the applicable CAR's. Cessna's position with respect to fuel system compliance and CAR 3.444 is "it is Cessna's belief and opinion that the 172P meets the requirements of the regulations and is in regulatory compliance". Cessna's position with respect to the unsafe condition is that the field service history of in excess of 20,000 airplanes needs to be examined to support the FAA position, and they have requested FAA provide details of the field reports we have received. In closing, Cessna states that "it is Cessna's plan to initiate a significant investigative program to identify and isolate any condition in the integral fuel system that may be unsafe. A schedule, as well as, a program plan will be provided to the FAA in the near future". This statement is now over 30 days old and no information has been provided to FAA on this issue.



 Formally notify Cessna that we do not concur with the positions presented in their letter of April 10, 2000.


Supply all incident/accident reports identified to date, which appear to involve these issues to Cessna.


Determine with Small Airplane Directorate oversight the best method to further issuance of an Advanced Notice of Proposed Rulemaking, with some form of relieving action to preclude grounding this fleet of airplanes.


PREPARED BY: Jeffrey D. Janusz ,








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