About 4 weeks ago we took-off for the Yukon for a 2 week vacation. Canada’s vast expanse had us covering 2500 nm for about 16 hours of flying – one way (CZBM – CYQT – CYQR – CYXJ – CYXY). This happened to be an excellent test to follow-up the electronic ignition ( emag ) installation on the PA-30.
By observation and on the basis of the expectation mentioned in the last article, both have proven to be quite agreeable. To be ascertain of accurate measurements, every tech stop we made, I ensured the 6 fuel tanks were topped up to the brim. The total fuel consumption evaluated by the uplift and the air time resulted in 14,2 gallons US / hour air time. 7,1 USG per side at peak EGT. Prior the installation a nice round figure of 16 USG / hour was the norm on the PA-30 (IO-320).
The fuel consumption included start-up, taxi, take-off and climb. The cruise fuel flow would yield a figure slightly lower. Cruise was set between 9 and 12000 feet above most convection affording a good ride for my favourite passenger. At those altitudes, the normally aspirated IO-320 would provide 21 to 19,5 inches of manifold and props were set at 2300 RPM. By the book, it would have appeared we were pushing 61% power however with hardly any loss of true airspeed. I keep cruise performance figures on a database. Old habit from a previous life… The lycoming engine graphs do not function anymore as they were build with Bendix magnetos times at 25 degrees before top dead center.
The emag manufacturers explain that the best fuel economy will happen above 6 to 7000 feet. Others like Surefly will not mention any numbers on fuel savings. They do save fuel !
As mentioned in the previous article, the goal here with the installation of the emags was to avoid future expensive magnetos overhaul every 500 hours. Mission accomplished. Otherwise not withstanding the 3 years amortization of the installed units, it must be said that cold starts are a hoot! When you hit the starter, one has just enough time to observe one prop blade go by and a first cylinder ignites into life. This is as quick as a well tuned automobile.
Of course for fuel injected engines, hot starts remain interesting as the fuel contained in the fuel lines still vaporizes. A good prime is always a must. So far I still have to count a couple of blades prior startup per say.
Now, I have to wait for a cold winter day and cold soak the PA-30 out of the hangar and attempt a start. Of course, it is a good idea to preheat a light aircraft engine such as the ones used in general aviation. Regardless, a test will be interesting.
Anyways, this is a far distance from this august afternoon, or so it seems. There remains a load of places to visit.
You have a question? Do not hesitate to write marc@aviationcommonsense.net