A Lead Mechanic and an Inspector with 'Inspector Authorization' (IA); report on their involvement with 100 hour Annual Inspection of a Piper PA25-235; that was later found to have several discrepancies.

Narrative

I performed a 100 hours inspection in accordance with Advisory Circular 43.13; 100 hour inspection form. During the course of this inspection; I performed a magneto inspection as per Airworthiness Directive 99-04-04 (impulse coupling) even after such Slick magnetos were replaced by me in April 2007 (about 290 hours ago). Sticker supplied to customer by mail; not placed in the book; reason why FAA representative did not find it; and considers magnetos total time unknown; inspected/lubed/checked points gap and the engine timed as per Lycoming O-540 B2B5 engine Maintenance Manual to the value of 25 degrees specified. The 100 hour inspection form mandated to remove all spark plugs; checked in the Champion spark plug cleaner/tester machine Part # CT-475; verified and re-gapped as required; at that time no plug was found carbonized nor defective by the Champion cleaner/tester machine Part # CT-475; the plugs removed from the engine were the same installed back; with the proper rotation according with Lycoming O-540 B2B5 engine Maintenance Manual's Champion spark plug recommended rotation charts. During the checks performed by the FAA Representative; the muffler was determined to have cracks; which after inspected by the engine repair shop was determined to have no cracks; so was reinstalled in the aircraft. This muffler installed and approved by the FAA later was found to be installed incorrectly; the clamp on the left-hand side of it is missing and the engine repair shop determined that it does not require a second clamp installed in the assembly. Maintenance Manual indicates 2 clamps Part #14235-08 are required to secure the exhaust stack to the muffler. The tubes' already coming apart due to the lack of any clamp at all in the muffler assembly. Supplemental information from ACN 820670: One of our competitors performed maintenance on the aircraft and stated that they found the left magneto set at 29 degrees and the right magneto set at 27 degrees. When our Mechanic performed the 100 hour inspection on the aircraft he stated that he performed all maintenance in accordance with the applicable Maintenance Manual. I cannot explain to you how the magnetos got to the settings they were found at. I do know that on several occasions the glider association brought us the aircraft because it was out of time. They tried to adjust the magnetos to help them start the plane better without a light. They have been witnessed by us as well as others performing maintenance on the aircraft. When the engine repair shop performed maintenance on the plane it had over 50 hours of flight time on it. Subsequent to the 100 hour inspection; one of the people connected with the glider association had discussed #1 cylinder having an oil leak and Mr. X decided to change the plugs every 8-10 hours until they could put the aircraft down long enough to fix the problem. This had nothing to do with me. They also told me that all of the bottom spark plugs were unapproved for the aircraft. Both horizontal stabilizers had fabric repairs accomplished with no documentation. I do not know when the repairs were made since there was no entry. The engine exhaust system had fabricated clamps installed after the 100 hour inspection and annual were performed. The FAA told me that when they re-inspected the aircraft that they could not find the Airworthiness Certificate and the Aircraft Registration. They were behind the pilot's seat. I cannot be held responsible for things that happen months after I perform an annual airframe inspection. Airworthiness Directive 99-04-04: Textron Lycoming Service Bulletin #537 states that when service history of the magneto is not unknown; an initial inspection of the Slick magneto impulse coupling within 10 hours of the effective date of this Airworthiness Directive and thereafter at intervals not to exceed 250 hours time-in-service. Callback conversation with Reporter revealed the following information: Reporter stated the Textron Lycoming O-540 engine Illustrated Parts Breakdown (IPB); shows two clamps required for the engine muffler exhaust stack.