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Hollis, write in and tell us exactly what you mean by "the
main gear unlocking". I have a feeling you mean something much less
disastrous than the gear over centre link popping up (unlocking) and the
gear folding into the well or partially so.
I know that the pump can give the odd burp now and again to
maintain the pressure. This can be due to internal or external leaks,
spool valves in the wrong way or maybe some air in the system. But in my
experience it does not mean that the gear overcentre link has become unlocked,
which would allow the gear to fold. The rat trap spring has to fail to
allow this to happen.
I have gauges on my hydraulic system and from my observations
it is very difficult to establish what is happening. Most of the time my
system will behave perfectly, as evidenced by observation of the gear going up
and down. However the odd time, the hydraulic system will push the gear
down perfectly, the pump stops,the low pressure gauge will show a pressure of
650psi and then it starts to bleed off. The pump cuts in for less than a
second, restores the pressure and the cycle repeats.
We had a long discussion on this on the LML. I decided
to do nothing about it as it was not dangerous even if inconvenient and the
problem appears to have faded into the back ground. No burps over the last
month in the hangar or on the taxiway/runway. Maybe it was air or the
infamous back to front shuttle valve.
Please tell us Hollis in words of one syllable, if possible,
just what happened when your gear "unlocked". We all badly need to
understand this and must assume the worst until you tell us
otherwise.
Regards
Ian Crowe
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