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.

CPCP Basic

CORROSION PREVENTION AND CONTROL PROGRAM (CPCP)

1. Introduction

A. As the airplane ages, corrosion occurs more often, while, at the same time, other types of damage such as fatigue cracks occur. Corrosion can cause damage to the airplane's structural integrity and if it is not controlled, the airframe will carry less load than what is necessary for continued airworthiness.

(1) To help prevent this, we started a Corrosion Prevention and Control Program (CPCP). A CPCP is a system to control the corrosion in the airplane's primary structure. It is not the function of the CPCP to stop all of the corrosion conditions, but to control the corrosion to a level that the

airplane's continued airworthiness is not put in risk.

B. Complete the initial CPCP inspection in conjunction with the first SID inspection.

2. Corrosion Prevention and Control Program Objective

A. The objective of the CPCP is to help to prevent or control the corrosion so that it does not cause a risk to the continued airworthiness of the airplane.

3. Corrosion Prevention and Control Program Function

A. The function of this document is to give the minimum procedures necessary to control the corrosion so that the continued airworthiness is not put in risk. The CPCP consists of a Corrosion Program Inspection number, the area where the inspection will be done, specified corrosion levels and the compliance time. The CPCP also includes procedures to let Cessna Aircraft Company and the regulatory authorities know of the findings and the data associated with Level 2 and Level 3 corrosion.

This includes the actions that were done to decrease possible corrosion in the future to Level 1.

B. Maintenance or inspection programs need to include a good quality CPCP. The level of corrosion identified on the Principal Structural Elements (PSEs) and other structure listed in the Baseline Program will help make sure the CPCP provides good corrosion protection.

NOTE: A good quality program is one that will control all structural corrosion at Level 1 or better.

C. Corrosion Program Levels.

NOTE: In this manual the corrosion inspection tasks are referred to as the corrosion program inspection.

(1) Level 1 Corrosion.

(a) Corrosion damage occurring between successive inspection tasks, that is local and can be reworked or blended out with the allowable limit.

(b) Local corrosion damage that exceeds the allowable limit but can be attributed to an event not typical of the operator's usage or other airplanes in the same fleet (e.g., mercury spill).

(c) Operator experience has demonstrated only light corrosion between each successive corrosion task inspection; the latest corrosion inspection task results in rework or blend out that exceeds the allowable limit.

(2) Level 2 Corrosion.

(a) Level 2 corrosion occurs between two successive corrosion inspection tasks that requires a single rework or blend-out that exceeds the allowable limit. A finding of Level 2 corrosion requires repair, reinforcement or complete or partial replacement of the applicable structure.

(3) Level 3 Corrosion.

(a) Level 3 corrosion occurs during the first or subsequent accomplishments of a corrosion inspection task that the operator determines to be an urgent airworthiness concern.

4. References

A. This is a list of references for the Corrosion Prevention and Control Program.

(1) FAA Advisory Circular AC120-CPCP, Development and Implementation of Corrosion Prevention and Control Program

(2) FAA Advisory Circular AC43-4A, Corrosion Control for Aircraft

(3) Cessna Illustrated Parts Catalog - part numbers P692-12.

(4) Cessna Service Manual - part number D2064-1-13.

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