AeroComposites Inc.

As I considered other propellers, I first ruled out the Hartzell. At the time, Hartzell recommended against using their props with either E.I. or high compression pistons, and I have both. Also, I am still mad at Hartzell for the way they screwed their customers over the numerous hub A.D.s they released during the last 10 years. Especially galling was the A.D. on the full feathering props (I owned a twin at the time) where we were offered inspections (at $1500 each) every 250 hours, or a real deal ($20K each) on new Hartzell props. I bought a pair of McCauleys at the time, and swore I would never do business with Hartzell again.

So, that left Whirlwind and AeroComposites. Even though we have an RV builder who is very high on the WW props, when I visited the booth and talked to them, I was not impressed. This may have been just bad luck in who I talked to that day. On the other hand, when I visited the AeroComposites booth, the man there knew every last detail of the props and the manufacturing process. They also had cut-aways of MT, WW, and their own prop, and I was very impressed with how the AC was built.

Then, in the RVator, Van's published some prop testing they had done, that confirmed my suspicions about the MT 3-blade and speed. So, I ordered an AeroComposites prop. http://www.aerocomposite.com/   Harry and John have a done a great job for me. I wanted a longer prop than usual for an RV, since I spend most of my flying time up high in the Rocky Mountains (home airport is 7650 msl). This results in lower indicated airspeeds, and also when I need to climb, I NEED TO CLIMB! So, I went with a 76" dia. I also needed a !.6" flange to rear of spinner dimension to exactly replace the MT. Finally, I needed a shorter than usual lead-time so I would have the prop in time for the Sun 100 race. This was no sweat for the AC crew, who basically build each prop to order.

I also ordered custom paint (+$500), since I have also tried to have a pretty airplane. I sent a drawing and color specs to the prop assemblers at American Propeller.

I think it looks pretty darn nice!!

The Rest of the Story

In March, 2004, I took delivery of a new propeller for my RV8. It was a beauty, painted black and gold to my design. A 2-blade, fiberglass and carbon fiber over a foam core, forged aluminum hub, nickel leading edge inserts…a high tech marvel. In initial testing it proved to be 4 kts faster than my previous 3-blade prop.

In April, I flew to Sun-n-Fun in Florida, to compete in the annual Sun 100 race for homebuilt aircraft. I took second place in the RV class at 196.5 kts, 8 kts better than last year. I should note that the prop was not the only change I had made.

With about 15 hours on the new prop, I put my wife Teresa in the back seat and headed home to Colorado (she had flown commercial to Florida). I felt that the prop was proven safe by then, especially after 30 minutes at 500 ft msl, 2700 rpm and 31” MP (yes, my new ram air system worked well too).

After a fuel stop in Mobile, I was westbound across southern Mississippi under a low overcast when I heard a sudden sharp noise, which was followed by a severe engine vibration. I assumed the engine had failed in some way. I immediately reduced power. The airplane was coming down faster than Paris Hilton’s panties. I was over a heavily wooded area. There was one farm field visible, but it was too small, and freshly plowed, and I had visions of the best case landing ending up inverted, and the worst, much worse. I was already talking to Gulfport approach, so I declared the emergency, and asked for the nearest airport. The controller said “Gulfport, 22 south”. I said “I’ll never make it”. After a brief pause, I was directed to a “turf, lightplane strip” 140 degrees at 6 miles. By now I had gone through the usual engine out drills checking mags and boost pump, changing fuel tanks, and I had found that at 2000 rpm the vibration was reduced. By flying at the RV8’s best glide speed of 100 KIAS, and about 12” MP, I was able to stretch the glide to Shade Tree airport, and made a normal landing from a straight in approach. I shut the engine down, and coasted off to the side of Shade Tree’s manicured 2800’ grass runway.

After using an airliner relay to tell approach we were down safely, we disembarked. The propeller immediately caught my eye. One of the metal leading edge inserts was missing. It was the out-of-balance condition that had caused the vibration.

After wandering around the seemingly deserted airport for a few minutes, we found an elderly man doing upholstery work in the back of a hangar. He directed me to a phone, and I called the airport owner, Danny Miller, and asked for permission to land. I then confessed the whole incident. He dropped everything at work and drove out to help. He insisted on putting my airplane in his hangar, and said I should leave it there as long as necessary. He then drove us to the Gulfport airport so we could rent a car. We stayed the night, and flew home commercial the next day.

I returned 3 weeks later with a used Hartzell prop I bought on ebay, swapped the props, and flew home to southwest Colorado.

I can’t say enough about Danny Miller. He is a true southern gentleman. I never felt the least bit of concern about leaving my airplane with him. He is also a fine fellow to sit around and drink a couple of beers with. If you are ever in southern Mississippi, drop in for some of the cheapest avgas in the area, and a visit. You should call first since it is a private strip, and there may not be anyone around. Shade Tree is MS82, not in your GPS, but it is in the www.Airnav.com database.

From now on, I think I will stick to certified props.

After I got home, I returned the prop to AeroComp so they could analyze the failure. Here is what they had to say--

John,

I wanted to provide you feedback on the results of our inspection of the propeller that you flew, which we received back last week. What we found, what we have concluded, and corrective action taken are as follows:

1. The blade surface under where the sheath had been bonded indicated very poor sheath adhesion to the blade. The surface was mostly smooth with limited adhesion imprint. We have removed many sheaths from our blades as part of process development and have found excellent/strong adhesion with blade surfaces appearing very different from what we observed on your blade. We did an acoustic sheath bond integrity test on the other blade and it passed, being normal. We then removed the sheath on this second propeller blade and found excellent adhesion, similar to what we have seen in the past on production blades.

2. The fine lines in the paint near the tip of the blade that lost its sheath are the result of operating the propeller with significant unbalance following loss of the sheath. We observed these lines in the paint on both blades. We saw this kind of minor distress once before when an owner operated his propeller for a period of time with essentially one dead engine cylinder on an IO-360. This engine condition produces major cylinder horsepower unbalance and significant engine vibration.

3. The most probable cause of the sheath debonding from the blade is that some aspect of the sheath preparation (grit blast, cleaning, priming, and final cleaning in that order) was not done properly. This led to a poor sheath bond on this one blade during blade molding. It is clear to us that the debonding of the sheath on this blade is an isolated occurrence and does not indicate a generic sheath bond problem.

4. As part of our corrective action, we have incorporated additional visual inspections in our quality control procedures, in the area of sheath bond preparation. Also, we have reviewed all our manufacturing quality control procedures to insure that they are consistent with producing high quality propellers.

5. As part of our corrective action, we have revised our Propeller Operators Manual (revision has been mailed to all customers) to include a sheath bond integrity test which owners are asked to perform periodically.

6. As part of our corrective action, we will continue to remove sheaths from production blades on a sample lot basis to insure continued high quality bond integrity.

Harry Griswold, AeroComposites Inc.
 

My Summary

First, I must say that the AeroComp guys are a class act. Their concern from the first time I called them was for my safety first, and the business impact of the failure second. I wish I could say the same for American Propeller, in Redmond, CA., who assembled and painted the prop. American was concerned only for their liability exposure, and could care less about my problems, being marooned in Mississippi, 1000 miles from home. On the contrary, Harry at AeroComp immediately offered to assemble another prop and send it overnight so I could get home. When I declined this offer (I was reluctant to try another prop until I knew what had gone wrong with this one), he said "Get on a commercial airplane and go home, we will pay all your expenses, and we can decide what to do after we both investigate the options".

In the end, I decided I did not want the AeroComp product until it had been tested more thoroughly. I requested my money back. I was paid in full for the prop, the custom paint job, the spinner paint, and all my extra expenses in flying home commercial, and in returning with a new prop to retrieve the airplane. You just can't ask for any more than that!

However, I must say that I am disappointed that the failure was a simple quality control problem. I feel there is no excuse for that, in this business, where lives hang in the balance. I guess I would have felt better if they had been fooled by an unknown resonance with my particular engine, or something more subtle like that.