AS 350 Negative "G"
Join Date: Nov 2004
Location: Cambridgeshire, UK
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theKite, it may be that a willi-willi could cause a microburst when the thermal that caused it stopped working. Normally it is the ice particles falling, but cold air might have a similar sink effect.
Dave Jackson might point you to the Frank Robinson quote on his website about coning and wee-wa.
That rotor overspeed might be something else the AAED we discussed the other day could eliminate. This would also improve the life of the rotor components...
Dave Jackson might point you to the Frank Robinson quote on his website about coning and wee-wa.
That rotor overspeed might be something else the AAED we discussed the other day could eliminate. This would also improve the life of the rotor components...
Last edited by Graviman; 20th Oct 2007 at 16:23.
Kite,
Simple, let me guess - Stainless blades and collective ballast incorrectly set up. Known problem number 238.
Simple, let me guess - Stainless blades and collective ballast incorrectly set up. Known problem number 238.
True, true, but I just couldn't resist.
Actually I did think of something similar after my smug post.
We had a 12e that had a tendancy to suddenly drop without warning.
Not funny when crop spraying at 3 feet AGL!!!!!!!!
We tried all the normal fixes, but it continued to happen and the aircraft was grounded.
We eventually found that the cause was badly brinnelled bearings in the main rotor grips.
On most helicopters the result would be an inflight vibration , but with the Hiller set up this didn't occur.
The Hiller has a fully gimballed head like the Bell 47 and therefore the grips only move in response to collective inputs. This lack of movement explains the lack of inflight vibration.
The sudden drop was caused by the roller bearings sitting on the peaks of the brinnel marks and then dropping into the valleys.
Replaced the head and the problem went away.
Actually I did think of something similar after my smug post.
We had a 12e that had a tendancy to suddenly drop without warning.
Not funny when crop spraying at 3 feet AGL!!!!!!!!
We tried all the normal fixes, but it continued to happen and the aircraft was grounded.
We eventually found that the cause was badly brinnelled bearings in the main rotor grips.
On most helicopters the result would be an inflight vibration , but with the Hiller set up this didn't occur.
The Hiller has a fully gimballed head like the Bell 47 and therefore the grips only move in response to collective inputs. This lack of movement explains the lack of inflight vibration.
The sudden drop was caused by the roller bearings sitting on the peaks of the brinnel marks and then dropping into the valleys.
Replaced the head and the problem went away.
Join Date: Jan 2005
Location: Darwin
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the ferret
YES! You just described the situation exactly.
Hard to believe, but the 12E was relatively new in Australia in the 80's.
I could not find a soul who could help me, and my boss sacked me for asking CASA's advice. (I got my revenge, but that is another story)
TK
Hard to believe, but the 12E was relatively new in Australia in the 80's.
I could not find a soul who could help me, and my boss sacked me for asking CASA's advice. (I got my revenge, but that is another story)
TK
