Frank Dillon, Tom Fleming, Jim Hoag, Bruce Powell
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Frank Dillon noticed this study of Army helicopter servocylinders but did not remember any helicopter hydraulic issues from his Centaur tour. Note with this study: Although the AH-1G is not specifically a part of this report the information rendered is directly applicable"
Jim Hoag: If “O” rings failed it’s quite possible due to not flying the helo (extensive maintenance?) and their drying out rendering them brittle. In my 16 years crewing UH-1s, OH-58s & AH-1s, I never had hydraulic failures.
Tom Fleming: When I was Service Platoop leader and aircraft maintenance officer, our only Hydraulic failures were enemy fire caused. Fortunately most of our gunship we had were 1B conversion to C models. The 1st new C models had a Hydraulic boost emergency that gave you about 3 cyclic pulls (so they said)) luckly we never had use them
Bruce Powell: I was in R&D (Aviation Research & Development) but had not heard of this study. Very few incidents related to Hydraulic failures in our UH-1H, AH-1G and OH6 aircraft have been mentioned on our website, that I know of, and those were probably related more to enemy fire than defective Hydraulic systems.
I made a mention of this subject in the Newsletter just in case someone remembers.
Google: The UH-1D "Huey" uses a two-channel hydraulic system with a total capacity of 10 pints (5.3 pints per reservoir), operating at approximately 1000 psi. It uses MIL-H-5606 red hydraulic fluid to power the servos, which assist the pilot with the flight controls (cyclic, collective, and tail rotor) to reduce workload. Each system has a pump that operates at different speeds, and a backup pump can activate if a primary pump fails
Centaur Website links related to Hydraulics:
https://www.centaursinvietnam.org/WarStories/WarEssays/E_KeepEmFlying.html
https://www.centaursinvietnam.org/WarStories/WarEssays/E_YearOfTheRat.html
https://www.centaursinvietnam.org/WarStories/WarEssays/E_EasterOffensiveMick.html
https://www.centaursinvietnam.org/WarStories/WarEssays/E_CamodianMedivac.html
https://centaursinvietnam.org/WarStories/WarDiscussions/D_SkilledHardLanding.html
https://www.centaursinvietnam.org/WarStories/WarDiscussions/D_CentaurAircraftResearch.html
https://centaursinvietnam.org/WarStories/WarDiscussions/D_TrustYourCrewChief.html
https://www.centaursinvietnam.org/WarStories/WarDiscussions/D_Ordnance.html