Blumlein's Plane Crash

[chriswood]

There is some information which repeats the assertion re tappet problems damaging the valve. I do wonder if as the tappet screw comes undone sufficiently, it catches the top of the valve stem putting a side force on it causing the valve to bend or snap. In the article below it says that aircraft Halifax V 9977 had just been through a precautionary procedure to adjust the tappets probably increasing the possibility of an error.
https://www.newscientist.com/article/mg1...tors-life/
Also I found a scan of the original RR manuls posted here
https://ww2aircraft.net/forum/threads/ro...938.38267/

Chris