Firewall Forward - Engine

2005-04-17 - Engine clean-up. (10.0 Hrs).

This week, I got some more parts cleaned-up, and put away, but the big news was the near failure of Ed Anderson's engine. This is the first known case of an internal part failure on a rotary engine powered aircraft. Ten minutes after takeoff, Ed had a reduction in power on one rotor, followed by the other rotor. Previously, all engine failures were due to some external part (cooling, oil, etc.). Ed had to make another emergency landing (he's had a few others). The good news is that his engine kept running, at reduced power, and he made a successful landing. It turns out that his engine ate at least two of the apex seals on one of his rotors. Did I mention that his engine kept running?

This had a lot of people concerned, and there was a lot of speculation as to how this could happen. No one is sure exactly what the cause was. Three pieces of information: (1) Ed was running without an air filter; (2) the apex seal grooves in both of his rotors were way beyond the Mazda limits; and (3) Ed was not using Tracy Crooks improved apex seals--he is now! The implication is that his engine ingested some sort of foreign object, or perhaps the seals broke due to the out of spec slop in the grooves.

Since I have two junk yard engines, one of which ate the apex seals in both rotors, I decided to measure my grooves. It turns out that the grooves on my rotors are well within the specified limits. We are all concerned about what we might do wrong that could cause an apex seal to break.

Side sway test. One of the guys said to put a seal in the groove vertically and measure how much the seal could move at the tip (3/16" max). Mine was way less than 3/16".
Dealing with rust. At first, I didn't think much of this rust remover gel, but if you let it set long enough, it really seems to work. I'm pretty sure this stuff is the same thing as battery acid (sulfuric acid). There's no indication on the bottle, but it's hard to mistake that odor.
After rinsing, it leaves a greenish coating, kind of like an AN bolt, but not as bright. I'm not sure if this is good or bad. I'll keep an eye on these parts.
Spent several hours cleaning these parts. I thought I had almost all of the main parts of the second engine cleaned, but I found another tub full of dirty parts, so I will be doing this for a few more weeks.