Paul "OX" Harder
Member
I am putting this out to the Grove airfoil geared RV-8 community. I finished my -8 in 2010 and have put about 160 hrs since then. In that time on four occasions I have experienced what I would call a very low frequency thump or vibration in flight. This thump has always occurred in a climb and in smooth air. No real particulars about the climb (twice three or four minutes after take-off and twice from cruise to a new altitude). When it happens, you feel it in the airplane not in the stick or rudder pedals and nothing that I can see from the cockpit seems to be moving also the engine parameters stay rock solid. My buddy (ex -7 driver and a multi thousand hour airline captain) and I have been discussing all sorts of possibilities (one of the incidences happened while he was flying the -8). We checked for loose stuff on the outside of the airplane, pulled the cowl checked all that stuff and couldn't find anything suspicious. So we decided to jack the airplane up and check the gear, wheel pants and tail wheel. After looking all that over without anything being unusual, my buddy was sitting on the creeper next to the left main gear and reached over and gave it a whack on the outside of the fairing. The gear oscillated side to side for about 2 seconds, dampened and then the right main started to oscillate. This went on, back and forth, for 30 to 45 seconds and quit. We both looked at each other dumbstruck! Neither of us had ever seen a landing gear do that. I jumped up in the cockpit and had him do it again and shazam, that was it. We were able to create the situation over and over. This made us feel great that we had found the problem, but now how to fix it? I spoke with the Grove people and they have never had anyone report anything like this. They, like us, feel that it is the prop wash striking the side of the gear in certain climb configurations. Neither of us feel it is a serious problem or that it has long term consequences for the airplane. I am planning on continuing to fly the -8 as is until it happens again. When it does, I am going to change power settings to see if that helps ( I have already tried slipping, loading and unloading the airplane to no avail). One last thing, my -8 is equipped with an IO-360 and a CS Hartzell Blended Airfoil propeller. So in conclusion, I am wondering if any of you like equipped -8 drivers have experienced anything like this and would love any input you may have. Also, this is in no way a criticism of the Grove gear. I love that gear and wouldn't own an -8 without it.
Thanks for your input!
Thanks for your input!