In what way have they failed?
From the FOI release 20170704 FOI12017 05825 DHAN100
ODH CAE Comments
The primary reason why glider airworthiness was questioned, leading to the 'pause', was a
failure
of the operation, maintenance and assurance system.
CAE (DDH) Comments
The engineering risks are as follows:
• Adopting New Standards & Procedures -
This will be the first time that the ac have been maintained and managed correctly for a number of years and, whilst MAOS accreditation has been achieved, there will be a heightened level of risk until the standards and procedures are fully embedded.
And there is plenty more gems like that in the other FOI's.