PPRuNe Forums - View Single Post - Harrier transition to and from hover
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Old 13th Mar 2014, 19:49
  #68 (permalink)  
John Farley

Do a Hover - it avoids G
Join Date: Oct 1999
Location: Chichester West Sussex UK
Age: 86
Posts: 2,206

Poor you! Over the years there have been many cases of odd trim changes.

When you think about it there are so many things that can affect the trim of a Harrier aircraft that it is amazing that there are two aircraft the same!

However you say you carried out rigging checks but not if you changed anything or things. So I would suggest the following:

Make sure the aerodymamic control surfaces are rigged within limits including the flaps when in the mid position.

Carry out the 450 knot check carefully and adjust the gauges as necessary to indicate zero on both.

From now on only adjust/change one thing per flight

If you are still unhappy with the 190kt gear down, flaps mid and nozzles aft situation look at your engine options.

Individual nozzle angles when aft selected. (having a rear one down even a little can change a lot of flow at the back end)

If these angles need changing re fly and do the 450 check and adjust again.

If still unhappy:

Swop the front nozzles (L/R)

Reset the 450 kts as required.

Finally - and this is the most likely cause of the confusion - swop the rear nozzles. These of course contain the engine trimmers which have been known to significantly affect overall aircraft trim with changing RPM at constant IAS. We have also found moving a trimmer's position in its own nozzle can also help.

Reset the 450 kts as required because in the end of course what really matters is the 450 kt trim setting as this affects gun aiming accuracy.

Good luck!

John Farley is offline