Piper Aircraft - Rear Spar Corrosion

 The FAA recommends that owners and operators incorporate the actions in Piper SBs 789A, 977, and 1006 based on the applicability of the individual SB. Due to similarity of design (steel plate 66762-00 adjacent to aluminum spar) and since improper maintenance or painting procedures have been a contributing factor in past service reports, all PA-28, PA-32, PA-34, and PA-44 airplanes are susceptible to this corrosion development. 
             Therefore, the inspections in the SBs should be implemented for all PA-28, PA-32, PA-34, and PA-44 models. We recommend that all the actions be taken within 100 hours. We further recommend inspection and incorporation as soon as feasible, but no more than 100 hours, for those airplanes at higher risk due to age, environment, lack of protective coatings, etc., as discussed above. We also recommend that owners and operators incorporate the actions in Piper SB 1244B following the compliance time in the SB.

SAIB: CE-11-12R1  Date: December 2, 2015

Severe corrosion

CESSNA 510           20/08/2015
Severe corrosion on emergency escape hatch door.
During a pre maintenance inspection a large isolated patch of corrosion was noted on the lower outer skin of the emergency escape hatch door. This area wasn't included in any of the scheduled inspections for this input but was visible during the pre-maintenance walkaround.

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.

To Blend or Spot Remove Damage

Documenting Corrosion Damage: Antenna Site

Filiform Corrosion

To help prevent filiform corrosion development, the airplane should be:

(a) Spray washed at least every two to three weeks (especially in a warm, damp environment).

(b) Waxed with a good grade of water repellent wax to help keep water from accumulating in skin joints and around countersinks.

(c) Keep the airplane hangared to protect it from the atmosphere.

(d) Fly the airplane to promote aeration of enclosed parts.

(e) Ensure all vent/drain holes are open to ventilate the interior of airplane.

(3) To remove filiform corrosion once it has been discovered:

(a) Remove paint from corroded area.

(b) Remove corrosion by sanding area to metal surface, using either a ScotchBrite pad or 320 grit sandpaper (aluminum oxide or silicone carbide grit).

(c) Clean and refinish surface.

Corrosion Control for Aircraft (Part 1 of 2)