PPRuNe Forums - View Single Post - TR malfunctions for beginners - a refresher lesson!
Old 26th Feb 2013, 12:27
  #2 (permalink)  
Thomas coupling
 
Join Date: Aug 2000
Location: UK
Posts: 3,680
Likes: 0
Received 1 Like on 1 Post
From DK:

T/R control loss
Mainly for TC ... thanks for the note and wish I could exchange my words for a couple of gold bricks!

To answer your note.

Following recognition of the TRF situation, I teach an immediate reduction in power ... (lever fully lowered) My use of the word 'immediate' depends on the power in use and airframe speed at the moment of failure. High power, low speed ... no upper limit. Low power ... highish speed, the lever can be lowered more leisurely. To enhance the simulation, I also 'induce' some airframe fibration with collective lever 'fluttering.'

Either way, the aim is to regain control and prevent further RIGHT yaw (USA machines) by allowing the airfame to return from 'right to left' past the 'dead ahead' position to establish a steady state descent in the '10 o Clock' position which requires right cyclic. With control regained, a combination of speed and power allows stable flight in the '10 o Clock' position to be established AND/OR a variation in distance flown and rate of descent as necessary.

With a suitable landing site available, a descent is initiated to around 20 - 30 feet AGL at the lowest achievable speed. As the airframe sinks to the surface, collective lever is raised to arrest ROD with a cyclic flare used to reduce forward speed. With the increase in power, airframe commences the original yaw to the RIGHT which is allowed as far as the 'One o Clock' position when throttle is closed for a low speed EOL. Cyclic is pushed forward to co-incide with the airframe approaching the dead ahead 'twelve o Clock' position while allowing the aircraft to partially touch down on the rear skids to assist a dead ahead 'run-on' landing. Even so the airframe is still likely to continue its left yaw, which as noted in a post above, can be minimised using a right cross wind giving greater drag on the right skid.

I hasten to add that my notes must neccessarily apply to the type on which I've experienced my two total T/R failures, being the cable operated Enstrom T/R control system where the failed cable wrapped itself around the T/R to seize the transmission. The other total failure being a straightforward break in the T/R drive shaft.

My 1999 Biggin Hill Air Fare failure being the less difficult left hand CABLE breakage which allowed use of left anti-torque pedal, but leaving no right pedal control for left yaw. I hope these somewhat neccessarily convoluted notes help an understanding of these failures. and I'd happily chat further with interested parties by PMs. Safe flying to all. Dennis K.
Thomas coupling is offline