The Hurricanes LF363 and PZ865 are quite similar in age and as can be seen have very similar TT figures. Following the crash landing, of LF363 on 11 Sep 91, it spent 7 years on the ground awaiting and undergoing CAT 4 repair.

If you were to wind the clock “back”. By how much would you wind it back? To zero?

If so in the following 25 years, from return to service, (29 Sep 98) it has flown just over 122 FH per year – somewhat above the 100 FH annual limit.

I haven’t asked but I would draw the conclusion that the clock was simply paused. In my experience engines do tend to be zero hour following major maintenance/overhaul. But airframes don’t. Sometimes airframes have their Fatigue Index (FI) re-calculated but that is based on monitoring equipment data. At the time no such data was available.

As a matter of interest PZ865 was fitted with a system called Hurricane Load Assessment (HuLA) system. This aircraft has 96 strain gauges installed across the airframe all connected to a data logger. The system was installed just prior to May 21.

A few years ago, I was heavily involved in the CAT 4 repair of a Chinook helicopter. We didn’t wind the clock back on that as part of the process.

As far as the Dakota is concerned. It was used by the Canadian AF before being placed on the UK MAR in 1969. It was then used for trails until 1992 and joined the BBMF in Mar 93. Its low TT is probably due to its lack of “commercial” use.