AD/CESSNA 400/92 Amdt 1 - Wing Front Spar Lower Attachment Fittings (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Cessna 400 Series Aeroplanes

AD/CESSNA 400/92 Amdt 1

Wing Front Spar Lower Attachment Fittings 3/89

Applicability: All 400 series aircraft, except for models 404 and 441.

Requirement: 1. Remove the fairing between the wing and carry-thru and gain access to the wing front spar lower attachment fittings P/N 0822550.

2. Visually inspect the upper and lower edges of the lug of each wing fitting, looking for fatigue cracks as shown in the figure.

3. From inside the wheel well, visually inspect each visible wing fitting for stress corrosion cracks and associated surface pitting in the area shown in figure A.

Note: It is not necessary to remove the primer for any of the above inspections.

Compliance: Prior to exceeding 5000 hours component time in service, or prior to the issue of the next Maintenance Release after 22 March 1989, whichever is the later. Thereafter, reinspect at each scheduled inspection for issue of a new Maintenance Release.

Wing Fitting Showing Typical Cracking

Note: Fitting Shown removed from aircraft for clarity

Figure A

Background: Fatigue cracking has been discovered in the wing fitting from an Australian-registered Cessna 310R with 6500 hours time in service. No abnormality could be found in the fitting or the aircraft's history. Since then, stress corrosion cracking has been found in a similar wing fitting in a Cessna 402C with 6400 hours time in service.

There is insufficient evidence to regard either of these as isolated occurrences: either or both may be expected to occur at a later time elsewhere in the fleet of Cessna twins which use the same generic wing fitting. A simple repetitive visual inspection has therefore been introduced.