B757-300
Maintenance Airframe; Maintenance Powerplant
Communication Breakdown; Other / Unknown; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft; Equipment / Tooling; Procedure; Human Factors
I was assigned four airplanes: A; B; C; D and a crew consisting of nine people; plenty to accomplish the work required for that night. I was working under the direction of Lead Mechanic X; he wanted to address a specific item in Aircraft D that a previous Lead wasn't comfortable performing. He [Lead Mechanic X] wanted to get people trained in performing the Job Card; as he requested four specific people of his choice to perform the job; at which I added two more people very proficient; all other aircraft maintenance was done without incident. However; Aircraft D had some difficulties; we didn't have the right equipment and no parts to replace the part if it failed; (Altitude Pressure switch).Management assumed we had the parts and equipment to finish the job. We removed the Pressure switch and started to test; [Altitude] Pressure switch failed; then we moved to the test of the EPR and found out the equipment was registering a leak which we couldn't find the source. The Supervisor determined the technicians weren't operating the equipment correctly and ordered us to put everything back and he would cancel the job cards; which he did. Then we ran the engine and found an EICAS message that won't [go] away. Also; the Fuel Governor was leaking at a rate of 16 drops per minute. Supervisor contacted Technical support and advised us that message wasn't a big deal; it eventually would go away. I didn't feel comfortable stopping the test in the middle of the work and putting all that we took apart back without finding out if the Pressure switch was ok; or if we had an EPR leak; or if the EICAS message and fuel leak was related to we [us] disturbing the system.  We should have finished the test and found out either the system was operating satisfactorily; or if not; what corrective action we needed.
An Aircraft Maintenance Technician (AMT) reports not feeling comfortable with an order from their Maintenance Supervisor to stop all testing and reassemble all the items they had taken apart after an Altitude Pressure switch had failed and an EPR leak was discovered on a B757-300 aircraft. The supervisor canceled the Job Cards and noted the technicians involved were not operating equipment correctly. Replacement for a failed Altitude Pressure switch was not available.