B757-200
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Flight Deck / Cabin / Aircraft Event Illness / Injury
General Physical Injury / Incapacitation; General Maintenance Action
Procedure; Human Factors; Environment - Non Weather Related; Aircraft
After finishing my assigned aircraft; lead directed me to assist 2 other mechanics in spoiler EHSV (Electro-hydraulic Servo Valve) change. One of the mechanics assigned to that aircraft was going to do the replacement the other was in the flight deck operating the spoiler and hydraulics as required. So I was assigned as ground mechanic giving clearance to the flight deck mechanic to power on/off hydraulics and spoiler. Mechanic replacing valve requested hydraulics on and spoiler deployed. I relayed the message to flight deck mechanic; when mechanic removed spoiler lock; the spoiler came down and caught mechanics arm for about 15-20 seconds then shot up and deployed releasing his arm.
I was directed by my lead to follow a section of Maintenance Manual that only included the replacement of the EHSV. I was removing the spoiler lock but it was wedged in there so we had cycled the spoiler. I tried to remove the lock with hydraulics off but I couldn't; so I asked the guy in the cockpit to turn hydraulics on and put the spoilers in the up position. With hydraulics on I was able to remove the spoiler lock and as soon as I removed it the Number 1 spoiler came down on my hand and began to crush it. After about 30 seconds of having my arm/hand crushed the spoiler came up and eventually released my arm. I was using AMM (aircraft Maintenance Manual) 27-XX-XX. Flaps were supposed to be down but they were locked out by avionics which led me to access the EHSV valve over the wing.
B757 Technicians reported that the spoiler lock was removed causing the spoiler panel to come down onto a Mechanic's hand.