This is an old one, but was hugely significant at the time, and will always remain so. I recently met a friend of one of the deceased, and I remembered the accident from 20 years ago when it was mentioned.
It impacted the ground at Easton Neston, near Shutlanger, 2 miles NE of Towcester directly beneath power lines without disrupting the electrical supply. There was no fire. The flying controls were found jammed by a tool.
The next of kin of the two persons on board went to court, and were awarded £270,000 in damages after suing the aircraft’s owner for negligence during maintenance.
Was the owner not on board? Sounds like not.
I remember this too, and IIRC how this and a couple of similar accidents highlighted the importance of counting tools in and out when working on Yak 52s in particular, even more so that other planes. Apparently there is a spot where a loose tool can easily jamb the elevator.
Also a shield was devised to prevent loose tools from getting to the spot in question, even if they were floating around in the fuselage.
Reminds me of an over-exiting flight of my acro-instructor. After flying the down-line a hammerhead turn, neither the student nor he could move the stick more than a few mm bachwards…
Pulling together with full force they narrowly avoided the ground (and/or inflight wings off) and somehow made it back.
At the field they found a silver cigarette case that slid back in the upwards part of the hammerhead and had jammed the elevater cable.
Never found out who lost it and when…