This is what the NART said about the misuse of STFs in 1998
"in some instances, formal mod action·had never been taken to supersede STFs, even though the installation of the equipments concerned on ac had became commonplace. Overall, a significant number of the 24 currently extant STFs had been in existence for a considerable time and were no longer being managed as temporary trial fits iaw the regulations in AP100B-Ol, Order 1120. Furthermore, some other STFs were routinely resurrected as required, normally on a yearly basis and for particular detachments."
And what an inquest (XV230) witness said about the misuse of STFs in 2008
"my interpretation would be you had an urgent operation requirement, special trials fit onto an aircraft, take it to theatre, get the job done, bring it back, take the equipment off. Whereas, we were doing go to theatre, take it back, on to a different aircraft, that goes out. ....... Okay, what had happened was when we first arrived in theatre, the problem is you do not have ready access to this equipment in the UK. So you often arrive out in theatre to an aircraft that has got, in this case I believe it was four or five separate special trials fits fitted to it, and that is the first time you have really got, to get to grips with it again. Somebody at Kinross had tried to be helpful when they produced like a local briefing package where they had in the back of the release to service document for each special trials fit they made, sort of make a waiver of, if you are going to do air to air refuelling you need to pull the circuit breaker or not use this particular item."
The misuse of STFs was also mentioned in the CHART report of 1992,
"STFs do not generate formal follow-up engineering documentation nor CA release and aircrew manual amendment action. Furthermore, there have been instances where tradesmen have been compelled to rectity faults on STFs without adequate support documentation (eg wiring diagrams ). Whilst the STF process is a legitimate means of introducing changes to an ac , it should be a short term expedient . However; the system bas been abused and a case was noted where an STF had existed without a SD or a cover modification for over 8 yrs. There is the potential for airworthiness to be compromised by these procedures ".
It is little wonder we lost aircraft and brave men.
DV