B737-800
Maintenance Airframe; Maintenance Powerplant
Maintenance Lead Technician 15; Maintenance Technician 34
Communication Breakdown; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Aircraft; Human Factors; Procedure
I supplied a non-compliant part to an AMT (Aircraft Maintenance Technician) who then installed it onto a cargo door which then was used on our aircraft.Currently [technician] is working a skin change on a 737 forward cargo door. While drilling up a pre-shaped skin it was realized that this skin was not fabricated for use on this MPN (Model Part Number) or model door. Discussions [on] this with the crew; it came up that one of these pre-formed skins had been used in the past for [the] same model; door.A review of the records shows that earlier this year [technician] produced a 737-800 cargo door by installing a skin pre-fabricated by [company] drawing 52-xxxx-xxx.The skins fabricated per the Engineering Order/Drawing are for a different MPN / model aircraft. This alone does not make these skin unusable but the fact that engineer based their approvals on a different MPN and aircraft model type when approving the material substitution; does.The original substitution approvals were for an original skin bonded from two layers of [aluminum]; substituted for one single thickness skin of for the aft cargo door of a 737-200/300.We installed this [modification] on a forward cargo door where the original skin was; the Engineering Order as stated does not cover forward cargo doors or 737-800s. To use the SRM (Structural Repair Manual) material substitution chart in an effort to allow for the substitution of a T42 skin vs a T3 skin requires additional thickness; due to the different heat treat properties.Therefore the skin installed is an out of compliance situation.
B737 Maintenance Technician reported that multiple cargo door repairs were made using an incorrect-thickness material.