Priming - How?
Joined: Sep 2001
Aviation Qualifications: CPL
Posts: 2,787
Likes: 208
From: Toronto
Starting below -10C is where it starts to get interesting; -20C was even more fun when I visited Sudbury, Ontario on a cold March weekend. Taxiing in I noticed that all the a/c in tiedown had on engine blankets and an electric cord leading away. I felt rather naked.
Starting began with a preheat; after a POH prime with six shots did not do the job, the mechanic took over to work the prime while the lucky apprentice pulled the prop.
Engine blankets help keep the heat in between flights, but a couple shots of prime doesn't hurt in -10C in a C-172 that has been flown in the last hour.
The most important trick is to conserve the battery and not burn out the starter motor with repeated attempts. If it doesn't fire up on the first or second try, find somebody who knows the airplane.
Starting began with a preheat; after a POH prime with six shots did not do the job, the mechanic took over to work the prime while the lucky apprentice pulled the prop.
Engine blankets help keep the heat in between flights, but a couple shots of prime doesn't hurt in -10C in a C-172 that has been flown in the last hour.
The most important trick is to conserve the battery and not burn out the starter motor with repeated attempts. If it doesn't fire up on the first or second try, find somebody who knows the airplane.
Joined: Jan 1999
Posts: 6,209
Likes: 2
From: north of barlu
Do Lists.........A fire in the making !
The usual reason for intake fires on starting is the time between the priming and turning the start switch.
I have to lay the blame firmly at the feet of instructors for the way that the majority teach the use of check lists, these lists are used as "do lists" that students slowly and deliberatly follow.
Most of these lists result in the tyro pilot taking a long time between prining the engine and turning the starter, this as a number of people above have rightly pointed out results in the priming fuel running down into the airbox risking an intake fire.
Staring the engine should be a memory drill so that the very minimum time is taken from the first prime untill the engine is stable at the recomended idle RPM and the engine T's & P's have been checked, only then should the check list be used to check that the correct checks have been done. This is why it is called a check list.
Starting a light aircraft engine is not rocket science so why do instructors try to teach it like it is?
I have to lay the blame firmly at the feet of instructors for the way that the majority teach the use of check lists, these lists are used as "do lists" that students slowly and deliberatly follow.
Most of these lists result in the tyro pilot taking a long time between prining the engine and turning the starter, this as a number of people above have rightly pointed out results in the priming fuel running down into the airbox risking an intake fire.
Staring the engine should be a memory drill so that the very minimum time is taken from the first prime untill the engine is stable at the recomended idle RPM and the engine T's & P's have been checked, only then should the check list be used to check that the correct checks have been done. This is why it is called a check list.
Starting a light aircraft engine is not rocket science so why do instructors try to teach it like it is?
