747 pitot tubes

[onchanman]

I'm a non technical passenger who's flight from JNB to LHR was cancelled last week. From what I've been able to ascertain the aircraft arrived in JNB in the morning with a problem with a pitot tube. A spare was taken from the local stores and this was apparently found to be defective and the flight was cancelled at about 22.00
I suspect that the flight was cancelled at uch a late time deliberately so that there was no possibility of the airline (BA) rebooking us on other flights as they'd already all left. Cheaper to accommodate passengers in a hotel than pay other airlines to take them.
My question is, I suppose, how long does it take to fit a pitot tube and find out that it is defective? And also, how many pitot tubes for a 747 would they be likely to hold in stock in the local stores?

[vs69]

Depends on the airline and its holding or pooling policy with other airlines. We dont replace them too often on our jumbos, post fitment I think a system leak check is required. I would say its highly unlikely the flight was 'deliberately' delayed,more like everyone trying to pull all the stops out to get a jumbo full of passengers away and unfortunately the a/c wasnt serviceable in time. It happens.

[Tinwacker]

As this was a BA station my wild guess is that one pitot tube would be held for the B744 aircraft, SAA don't operate these aircraft anymore so no spare probe available from them.
As previously mentioned, a rare failure and I have never had to replace one myself. Access is a problem but the probe shouldn't take too long to replace then time for testing..
The probe heat is probably what failed and although the MEL will allow one for despatch the remarks are as follows:
Heater elements in one probe may be inoperative provided aircraft is not operated in visible moisture or in known or forecast icing conditions.
That may well have been the stopper after finding the spare was inop.

TW