There would be rather more than fabric repaired at the squadron level. An example is on 8 Sqn. (FK.8) over 8th and 9th August 1918, when according to the commanding officer (AIR 1/1671//204/109/26, page 8):

“…no less than ten machines had to be repaired in the Squadron. Of these, 6 machines were in ‘A’ Flight alone. The repairs done altogether entailed the following parts being changed :- 10 main planes, 2 tail planes, 8 ailerons, 2 petrol and oil tanks, and 1 set of radiators. In every case the machines were ready to fly by dawn on the day following the day on which they were damaged.”

I think any fabric repair was the least of their worries.