Cessna aft fin attachment fitting inspection

               FAA recommend that owners, operators, and maintenance technicians and inspectors visually inspect and confirm their findings using eddy current on the affected Cessna models utilizing aft fin attachment fitting, part numbers 0431009-1/-2/-3, for cracks and corrosion. This should be done repetitively at 100 hours intervals following inspection procedures described in the applicable Cessna SID located in the table of SIDs. Note that it may be beneficial for the inspection to be accomplished in conjunction with compliance to AD 80-11-04.
         FAA and Textron Aviation (Cessna) have been aware of cracking of the aft fin attachment fitting; and have previously issued a number of airworthiness publications to inform owner, operators, and maintenance technicians and inspectors. Cessna issued Service Bulletins (SE74-10 and SE78-62) in addition to the specific inspections noted in the referenced SID. Additionally, the FAA issued AC 43-16A, Aviation Maintenance Alert, Number 357, in April 2008 to remind inspectors to inspect the aft fin attachment fitting for cracks. Airplanes used for aerobatic use were noted to have a higher risk.

Classifications for Types of Operation

Cessna 152 
 The severity of the operation environment needs to be identified to determine the correct inspection program.

                   (a)  first find the category of your airplane’s operation based on average flight length.

                    (b)  find the number of hours and number of landings on the airplane, then find the average flight length based on the formula found below.

Average Flight Length = Number of Flight Hours / Number of Flights

               If the average flight length is less than 30 minutes, then you must use the SEVERE inspection time limits. For airplanes with an average flight length greater than thirty minutes, you must find the severity of the operating environment.

              Airplanes which have engaged in operations at low altitudes such as pipeline patrol, fish or game spotting, aerial applications, police patrol, sightseeing, livestock management etc. more than 30% of its life must use the SEVERE inspection time limits.

              For all other operating environments, inspections should be conducted using the