Chug,
Headbox changes were never done in the Seat Bay on the Mk10 as they were on a different servicing cycle and controlled differently. I would say the whole thing was designed in this way.
The Seat was serviced annually and controlled by the Seat Bay (Eng Tech W) whereas the Parachute Headbox and PSP were on 26 week cycles and controlled by the Survival Equipment Bays (SE Fitt).
We did usually try and keep the SE in line with the Seat where possible to keep things simple. Likewise, Seat Cartridges were I think 5 years and we tried to keep them in line with the Seat if possible (makes life easier!).
I think what you are asking is how often was the Scissor Shackle disturbed during an average year? Well on calendar, normally only twice a year, but every time the Seat was removed for access or loose article checks, it would be disconnected as part of the Seat removal, but never as frequently as every 50 flight hrs!
Last edited by Mortmeister; 15th February 2014 at 11:12.