I found them very helpful in a previous emergency in the old Rallye 880 we used to have many years ago, when the port fuel tank bung decided to spring a leak over the Fovant WW1 badges about 10 miles to the east and suck out Avgas all over the wing.
I had visions of the cover plate disappearing into some farmer's field. But fortunately it hung on - just! Luckily I spent my younger days there on a farm at Sutton Mandeville and so knew the area very well.
Returned to CA for more fuel and some gaffer tape before proceeding on my way after suitable refreshment.
I remember this special box you had to have for refuelling.
RD
