My friend's RV-14 has about 7 hours on it. Today he said he was trying to figure out what is causing a noise that sounds to be coming from down by his feet. It is only noticeable or occurring when he reduces the throttle for landing. Today he said he made some slow flights and while reducing the throttle no noise was heard. He says he has been running the engine hard ( more than I would, I broke mine in at 25 squared and I'm not burning any amount of oil, normal 1 quart in 8 to 10 hours). I'm wandering if he's not running the EXP239 very hard and reducing power too fast . He thinks it's perhaps backfiring when he is reducing power. I'm thinking of having him reduce power overhead tomorrow so I can see if I hear anything from the ground.
Thanks
Thanks