Commercial Fixed Wing
Maintenance Airframe; Maintenance Powerplant
Confusion; Training / Qualification
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors; Procedure; Manuals
While assembling a GE C2 transfer gearbox; I noticed a possible discrepancy in the way the shroud was installed on adapter of horizontal gearshaft. The manual has a note that reads: With adapter aligned as it fits on the transfer gearbox; the housing shroud must be installed at the 6 o'clock position. My concern is I may have installed the shroud incorrectly on possible 5 gear boxes in the past several months while performing maintenance under check and repair guidelines. If they were installed incorrectly it would not be evident because a gear backlash check is not required which would alert the mechanic to the problem. We do perform a pressure test. The pressure test would not alert mechanic to shroud being installed incorrectly. It is possible to install it in the 12 o'clock position and not know it on a check and repair the gearbox. In question are only check and repair gearboxes.The 6 o'clock position is only identified in the inspection/check figure. Even there it is not clear. Add to note in subtask that reads along with current note: The flat on adapter housing is 6 o'clock position. Also add line to logbook to verify shroud in 6 o'clock position. Add this note after current line 7 which calls to install horizontal adapter gearshaft package in gearbox housing.
Maintenance Technician reported discovering the transfer gearbox shroud for a CFM56 engine could be installed upside down and may have occurred on previous gearbox assemblies.