pedejd424

ADS arm micro switch adjustment fixed the snag. The airflow around the ADS arms causes them to flutter while the door is in transit. Extra play or an under adjusted switch caused circuit interruption when the door was opening. The RH arm switch was adjusted and air tested serviceable. Simple fix, complicated troubleshooting since snag could not be duplicated on ground. Thanks for input.

Maintenance replaced aux pump. Air test no change. Operated door open and locked, ramp open and locked, ramp closed and locked, door closed and locked in that order using manual control. Test successful, isolated to electrical issue. This model has ADS arms ( anchor arms ) installed for aerial delivery, wiring diagram shows if these arms are loose when retracted or switch is minimally contacting the power is lost to the ramp solenoid.. Sure enough techs went out and rattled the arm finding circuit being opened and ramp solenoid de-energized. Switch adjustment in progress. Test flight this afternoon. Fix sounds promising since air loads when opening door with the ramp closed are different than with an open ramp, possibly affecting a minimal contacting arm switch. Update to follow and thanks smoedog for the suggestion.

Going up for another test flight tomorrow. I will definitely check the operation using manual to rule out hydraulics. Maintenance has performed a fairly thorough check of wiring and terminals and are now in progress checking ramp components. Will post update.

Update on this snag, Maintenance has replaced the following components, Cargo door actuator, cargo door shuttle valve, ramp and door manifold, and carried out switch adjustments. Test flight today with no change. With ramp closed and locked the door reaches just short of the uplock and oscillates up and down. If you unlock the ramp and lower it slightly the door will completely go up and locked. Also when the door is open and locked the ramp fails to completely close and lock, once again there is a pulsation as the locks repeatedly extend and retract trying but failing to engage. If the door is closed and locked the ramp operates fine. Seems like a pressure bypass/hydraulic lock somewhere in the system.

Test flight procedure RCAF C130 332 E/H model. 30500 hours. On ground ramp and door control work fine when actuating door or ramp open/closed using electrical control. While in flight using ADS in flight deck ramp and door will open and close no problem. However when using door and ramp control from cargo compartment, ramp closed and locked then select door open, door reaches 4 inches short of uplock and begins to pulse up and down. If door is open and locked ramp will open normally, but when trying to close using ramp electric control ramp reaches closed position and pulses. Does anyone know of a common component that is bypassing hydraulic pressure? Additional food for thought while actuating ramp and door switches simultaneously, they will open and close without problem, providing the switches are held in position. Thanks and Hercs rule.