You may recall I reported a buzzing noise from the front of the aircraft some time back. Various causes were suggested (prop balancing, loose cowls, loose exhaust extension, worn/incorrect engine mounts). We eventually tracked it to the nose gear door opening in flight and/or failing to close after gear retraction. To further confuse the issue, this couldn't be reproduced on the ground, therefore airload was a factor.

The solution came in stages, replacing the main and nose gear actuators helped but didn't solve the problem. Replacing the nose gear door sequence valve also helped. Finally, replacing the nose gear door cylinder appears to have completely cured the fault.

Thanks to everyone for their feedback and faultfinding tips.

An interesting fact also came to light. Replacing the seals does not always fix an internal leak as excessive wear (the aircraft has 1000 hours) cannot be compensated for by a standard seal. In the case of the main and nose gear door, the hydraulic fluid simply leaked around it thus throwing us a red herring when the gear door still failed to close. The cylinders themselves may eventually require replacement.

Thought you guys might like the feedback

Regards,

--
Gerard O Connell
Melbourne, Australia
VH-LPD (LNC2)



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