A helicopter repair station Maintenance Manager reports on the lack of information in the Eurocopter MBB-BK-117 Maintenance Manual detailing proper orientation of the main rotor pitch change links during installation. Pilot had noticed a difference in one of the four links during his preflight.
Synopsis
A helicopter repair station Maintenance Manager reports on the lack of information in the Eurocopter MBB-BK-117 Maintenance Manual detailing proper orientation of the main rotor pitch change links during installation. Pilot had noticed a difference in one of the four links during his preflight.
Narrative
I received an inquisition from our Regional Maintenance Manager that a Main Rotor Pitch Change (P/C) link was found to be installed backwards on a MBB-BK 117C Eurocopter. He informed me that the PIC (Pilot in Command) found it on his preflight and the Base Mechanic was informed and made the proper logbook entries and the discrepancy was corrected at that time. The aircraft was just released out of the fixed base hangar after heavy maintenance was performed. I investigated the work order records and found that Mechanic 'X'; with over 20 years experience but new employee to the company; installed and signed-off the P/C link installation. It was inspected by Inspector 'X'; a veteran employee of the company.I then read the Maintenance Manual procedures. I initially found there to be no written instruction of the correct orientation of the P/C link in the installation procedures. Upon further review; I found a 'note' that appears in the removal procedures for the removal of the P/C links. The P/C links were already removed and therefore Mechanic 'X' was following the installation procedures only and would not have read the 'note' for P/C link orientation which is written in the removal section. The P/C link had the proper torque and had the proper safeties. This installation would NOT have caused a malfunction of the flight control system and only would have affected the track and balance adjustments of the corresponding main rotor blade.My recommendation to avoid recurrence of this event: First: Have Eurocopter move the 'note'; which contains only installation information; out of the removal section and into the proper section in the installation procedures.Second: I had a meeting with the fixed base maintenance staff and made them aware of the situation. I explained that the whole procedure should be read and all information needs to be taken into account. I stressed the inspection procedure that the fixed base hangar has in place and that it needed to be executed with perfect precision to prevent these occurrences.
NASA callback
Reporter stated there are four pitch change (P/C) links (rods). Each pitch change link lower rod end attaches to a separate bracket fitting on the main rotor swash plate. The upper end of the each link attaches to a blade control lever. The rod ends are also known as 'lollipops;' due to the shape of the rod end and the bearing inside. Both rod ends are replaceable and threaded into the link with two jam nuts to secure the rod end into the link. The lower rod end locking jam nuts are larger than the upper rod end locking jam nuts. One end has 'coarse' threads and the other rod end has 'fine' threads. Both are used to rig each blade during track and balance. Each blade is dot; color coded. The report stated yellow is the primary blade with green; blue and red to follow.Reporter stated that currently there is no response or movement from the Manufacturer; Eurocopter; to address the lack of information for the proper orientation of the pitch change links during installation. The FAA has told him they are trying to get Eurocopter to make revisions to their Maintenance Manual.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.