---------------------------------------------------------- RV-List Digest Archive --- Total Messages Posted Mon 05/17/10: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:22 AM - Flap Fuse (Ian) 2. 10:55 AM - Re: Flap Fuse (Denis Walsh) ________________________________ Message 1 _____________________________________ Time: 09:22:52 AM PST US Subject: RV-List: Flap Fuse From: Ian How about disconnecting the pushrods and checking for resistance to movement by moving each flap manually? Excessive current draw suggests that the motor is struggling. You could divide the movement in two - the motor to the push rods and the push rods to the flaps. If you feel no resistance to movement on the flap side then maybe there's some interference or tightness on the motor side. Could anything be misaligned, interfering or overtightened in motor to pushrod chain? Ian Brown "I have an RV-7a with 700 hours on her and a month ago the flap fuse ( 7.5amps ) blew on two consecutive landings. The fuse has never blown before in those 700 hours. I know I was well below the white arc, 10 to 15 knots below, on both of the landings. After I changed the fuse on those two, it went almost a month without ever happening again, then the fuse below twice more over the course of a few landings. It always blows on the downward movement, but the point at which it's blown varies anywhere between just barely having moved and being as much as 20 degrees when it happens." ________________________________ Message 2 _____________________________________ Time: 10:55:08 AM PST US From: Denis Walsh Subject: Re: RV-List: Flap Fuse The flap motor has a clutch and slips when the resistance gets too high, so it is unlikely that this is the problem, given the intermediate position of the flap when it occurs. I would look for an area of high resistance in the circuit. Check the switch for all connections. Check all crimps, and check the connections at the fuse. Check the connections at the actuator, and at the power bus. Lastly don't forget the ground side of the circuit. If all those check out, I would do a current measurement, and make sure the fuse is big enough. Remember the fuse is sized according to the wire size and length. Good luck and let us know how it comes out. Denis On May 16, 2010, at 5:20 , Ian wrote: > How about disconnecting the pushrods and checking for resistance to > movement by moving each flap manually? Excessive current draw > suggests that the motor is struggling. You could divide the > movement in two - the motor to the push rods and the push rods to > the flaps. If you feel no resistance to movement on the flap side > then maybe there's some interference or tightness on the motor > side. Could anything be misaligned, interfering or overtightened > in motor to pushrod chain? > Ian Brown > "I have an RV-7a with 700 hours on her and a month ago the flap fuse > ( 7.5amps ) > blew on two consecutive landings. The fuse has > never blown before in those 700 hours. I know I was well below the > white arc, > 10 to 15 knots below, on both of the landings. > > After I changed the fuse on those two, it went almost a month > without ever happening > again, then the fuse below twice more over the > course of a few landings. > > It always blows on the downward movement, but the point at which > it's blown varies > anywhere between just barely having moved and > being as much as 20 degrees when it happens." > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rv-list Browse Digests http://www.matronics.com/digest/rv-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.