UFCM
Meadowbank is correct. It is equally important to consider whether the BoI knew about previous Chinook crashes caused by UFCMs.
Boscombe stated in October 1993 that the Mk2 should not be released to service without an essential modification being fitted and, lacking the same mod, the Mk1 RTS was invalid; something they had advised of at least 4 years before as a direct result of previous crashes.
That is, an ESSENTIAL safety modification had not yet been developed, never mind trialled, approved, manufactured and fitted to either the Mk1 or Mk2, 2 weeks before ACAS said the aircraft was safe and stating no ESSENTIAL mods were outstanding.
I'm sure Lord Philip will be asking why this gem was apparently ignored by (or withheld from) all inquiries.