Inspector reported non compliance with AD procedures and deviations from repair instructions were discovered during maintenance of a C421 aircraft.
Synopsis
Inspector reported non compliance with AD procedures and deviations from repair instructions were discovered during maintenance of a C421 aircraft.
Narrative
During the annual inspection the work order was filled out to include the left engine required AD XXXX-XX-XX (To prevent failure of the starter adapter assembly) part 2; 3 (100 hour visual and 400 hour removal of the adapter and inspection of internal gears) inspections to be completed. The right engine required the same AD but only part 2 (100 hour visual inspection) was due on the right engine. The right engines work order discrepancy was reviewed and the assumption was made that both were due the exact same inspections since most times the engines times match up side to side. The left engines discrepancy was not reviewed accurately and the part 2 inspections were completed on both engines. Part 3 was not completed on the left engine. The work order program has a boilerplate discrepancy/ corrective action function so the left corrective action (and logbook entry) was made that stated both part 2 and 3 were completed when in fact part 3 was not done. The discrepancy was discovered on a subsequent inspection of the aircraft as the original torque seal was noted on the starter adapter leading the inspector to believe (accurately) that the starter adapter had not been removed since the engine was overhauled. The logbook was reviewed and the inaccurate entry was noted in the logbook. The starter adapter will be removed and the required inspection will be performed. The issue could have been avoided if the left engine discrepancy had been accurately reviewed for each engine and no assumptions made that the engines required the same inspections at any given time.
Second reporter narrative
During installation of the strakes the dimension given for the fore/aft location of the leading edge of the strake was found to allow the aft edge of the strake flange to protrude out past the structural frame by approximately .5 inches which would not allow the last flange fastener called out in the instructions to be installed in structure; but rather skin only with a gap of approximately .032 between flange and skin that would have to be pinched up tight by the fastener. In almost all of the provided drawings; the pictorial location showed the strakes located slightly forward of the dimension given on the install drawing. Verbal conversations with the STC (Supplemental Type Certificate) holder resulted in the holder giving instructions to move the strake fore/aft until the flanges of the strakes aligned better with the skin seams and underlying structural members (bulkheads) as well as covering as many existing fasteners as possible. Pictures of the locations prior to installation were submitted to the holder and texts and emails were received that said the location was acceptable to the STC holder. These instructions were followed and the installation completed.During a subsequent inspection of the work after the aircraft had been released for service the location of the strakes was called into question. Dimensional checks of the drawings verified the forward edge of the strakes were approximately .5 inches forward of the drawing location. Additionally several fasteners (rivets) were found to have not been installed in one of the internal doublers. Subsequent conversations were held and pictures given to the STC holder and they were still in agreement that the location was structurally sound and acceptable to them. The facility that called the location into question was going to obtain a deviation from a Designated Engineering Representative (DER) for the current location to make sure the installation was acceptable as is. The STC holder has been contacted and improvements to the drawings have been requested to make it much clearer for the locations and to obtain authorization to allow for minor deviations to the dimension to accommodate the differences in each aircraft.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.