Reliability ?
Jim, I don't really think reliability is a good word for smoke injectors.
If they have a hole and shoot oil into the exhaust pipe, they are working...but maybe they just work less over time
Since they have no moving parts, I'm not sure there is a true failure pattern but I would say from my experience ( about 150 gallons or so over the last three years) I never get more than about 30 gallons through them without taking the injectors out and cleaning them.
I am told that smoke oil really doesn't burn, it vaporizes and the residual mess can and usually does clog the injectors over time. I have used several and I really like the ones from Smoke Systems Helper because they have a fan shaped port with a small hole in the center. You turn the fan so that the oil is spread across the flame front and it is supposed to vaporize cleaner and use less oil. Seems reasonable and the airplane stays reasonably clean. I think we are pushing about 1/2 gal per minute but I could be wrong on that.
Flying with Bulldog Flight Team, we use a lot of oil and I have to clean the injectors about twice year. I use two of the fan style injectors and clean them by soaking them in lacquer thinner for a little while and then a large drill bit from the rear and then a small bit through the injector hole. Usually I run a thin piece of scrape metal, razor blade, etc. though the fan cuts and reinstall them.
I think cleaning smoke injectors is just a part of routine maintenance. I love my smoke system and would have one even if I never flew formation.
Bill
