I never leave the parking break on, unless running the engine checks, the reason is mainly due to the pressure on the O rings. As for the question about refuelling and fire.
I am aware of 3 cases where aircraft caught fire during refuelling. The first happened because the aircraft and the tanker were not earthed to each other, a spark jumped between the aircraft (Nortatlas) and the fuel nozzle, the rest is history. The second was also a result of an earth problem while the third was a fully armed F4 that was going through ‘Hot Refuelling’ procedure. The fuel hose was not attached correctly to the aircraft resulting in fuel escaping into the engine air intakes, the aircraft caught fire and the pilots jumped out. The rockets and missiles engines ignited and as a result the aircraft jumped the chocks and ran into an ammo bunker. No one was willing to deal with the fire, the only 2 who did were the airbase commander and his #2. (I also know of a case where an aircraft caught fire when 1 engineer worked on the oxygen system while the other repaired a window screen).
Lesson learnt: Always make sure that you and other have a quick exit from any situation, leave you parking breaks OFF, use them only when you are inside the aircraft or have no other option.
Brakes off, passengers out is the local rule at EHLE - enforced by the Duty Officer if necessary.
I once heard a story about the Rolls Royce Vulcan that caught fire. They lost the aircraft AND the fire truck, which was parked too close. Don't know if it's urban myth but it made me chuckle
I was never told why, but when I was learning I was always told to leave the brakes off when at the fuel pumps. I always assumed (as others have said) that it was in case there was an opportunity to move it out of the way.
As a related note I always used to put my seatbelt on before starting the engine. Now I dont just in case there is a fire. That said, in a Piper Archer, if there is an engine fire, you want to hope your passengers can move pretty sharpish otherwise your no better off really :wall:
I have always understood brakes off for Pilot Dar's reasoning. Also brakes off & chocked in the hangar for the same reasons. I also believe leaving parking brakes on long term strains the mechanism, though not too sure about that.
It's been my SOP since day one.
Parking break off at the pumps, and on the runway.
In both cases, it's so the aircraft can be moved (more) easily in an emergency. If it's the aircraft that is on fire, the cables/interior may be too damanged to easily disengage the mechanism later on. If it is something else, you want to push your pride and joy out of the way as quickly as possible.
Another 'procedural' thing that tends not to be written in any manuals/guides: Unfasten seat belt before shutting down. That's one for those who may occationally be wearing parachutes!
At my airfield, there is a "rivulet" in front of the pump. (Sorry, I hope this is the correct word for this) It is V shaped, fairly flat but it prevents aircraft from moving during the filling of the tanks, provided that the wheels of the main gear are in this channel. No need for brakes, no need for chokes either. The slope is slight to allow for an easy pulling or pushing of the aircraft if necessary. I now wonder why this kind of channel is not present in front of every pump.