11 April 2001

IN REPLY,REFER TO:
L417-02-01-105

Cessna with FAA participation has carried out extensive testing on new production Model 172R/172S
aircraft. Testing has been in accordance with a test plan jointly developed by Cessna and the FAA. The
purpose of these tests was to determine the reactions of a 172R/172S fuel system and a fuel-injected
Lycorning IO-360 engine to measured quantities of water deliberately introduced into the aircraft integral
fuel tanks in both ground and flight operations.

Three production aircraft were used for ground testing. FAA personnel participated in the conformity
inspection of each aircraft tank and participated directly in all testing.

Ground tests were conducted to estimate the approximate detection threshold of water contamination that
could be introduced into a relatively static fuel tank by three different methods. The greatest amount of
water found by any test method was then used in a comprehensive flight test program.

Flight testing was conducted on one of the three new production airplanes used in the ground tests. A
comprehensive series of test flight maneuvers were conducted. Additional tests beyond the scope of
normal certification testing were also included in the test profile to examine the behavior of the water
contamination under a number of flight and ground conditions. Preflight fuel sampling of the deliberately
contaminated fuel tanks was omitted so that the maximum amount of water established by ground tests was
present in the fuel tanks at the beginning of the flight tests.

All testing planned for the 172R/172S aircraft has been completed. There was no reaction of the test
aircraft's engine to the deliberate water contamination at any time during any of the flights. Postflight
examination of the aircraft integral fuel tanks revealed dispensed and detectable water contamination with
most of the drains exhibiting contaminated fuel upon sampling.

A similar test program using an older, carbureted model 172P is being developed per Cessna/FAA
agreement. It is anticipated that flight test procedures for the 172P will be similar to those developed for
172R/172S testing. Cessna and the FAA have met and are drafting the 172P test plan. This should be
completed in the next few weeks and will be submitted for FAA final review and concurrence. Cessna is
also working to obtain a 172P test airplane for the program.