Remember one failed start at Cottesmore. The rapid air system could manage a sim start of all four and a single engine rapid. Obviously the 6000 psi air could therefore be used 5 times and was very useful on landaways.
On this occasion the usual PoWWWWW was a more muted pow... The chief then suggested either another engine or the other bottles with almost predictable results - po.... and again p......
As radar I quipped in 'Any air in the bottles?' The chief assured us that the bottles had all been charged BUT took the little curved panel between the 1 and 2 engines off and found NO AIR. Same of the starboard side.
The conclusion was obvious and we all deplaned and handed the jet back for a proper BF! Can't remember if we flew that day.