---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 05/22/17: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:29 AM - Re: Flaps system tripping the circuit breaker (Fred Stucklen) 2. 11:33 AM - Re: Flaps system tripping the circuit breaker (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 05:29:54 AM PST US From: "Fred Stucklen" Subject: Re: AeroElectric-List: Flaps system tripping the circuit breaker First, the flap system in the RV's has a clutch for travel to both ends of travel, so the flap motor never actually goes into a stall condition. The motor current only goes up less than 2 amps over normal ground bases travel currents. Second, aerodynamic pressures on the flaps raise the flap motor current significantly. To the point That a 7 amp fuse or circuit breaker will definitely trip. And from my experiences in multiple RV's I Know that while flying, a trip can happen while extending or retracting the flaps. I strongly suggest that you need to increase the amp rating of your circuit protection to at least 10 amps. If you do that, your problems will go away.. All the planes listed below have had 10 Amp Circuit protections, and did not trip during flight.. Fred Stucklen N924RV 1395 Hrs Flying N926RV 875 Hrs Sold N925RV 2008 Hrs Sold One of my aviator friends called me to help him solving a problem in his RV-7 flaps system. He told me that occasionally, when he retracts the flaps, the correspondent Circuit Breaker trips. But not always, so he resets the CB and the flaps keep working normally. I asked him to measure the current during the flaps movement, and he measured 1 to 2 A when extending and when retracting, but he noticed that after full retraction the current went to 7 A. That explains why the CB (5A) trips. I think most of you know that the flaps system in an RV airplane is powered by an electric motor with 2 wires, which make the flaps work in both senses, just with reversing the electrons movement on those 2 wires. You also probably know that the motor doesn't stop at both ends if you don't release the switch, so the motor keeps turning even when the flaps reach full extension and full retraction. Now the question: which can be the reason for the current peak that the motor is reaching at full retraction? Any help welcome Thanks Carlos ________________________________ Message 2 _____________________________________ Time: 11:33:01 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Flaps system tripping the circuit breaker At 07:28 AM 5/22/2017, you wrote: >First, the flap system in the RV=92s has a clutch >for travel to both ends of travel, so the flap motor never >actually goes into a stall condition. The motor >current only goes up less than 2 amps over normal >ground bases travel currents. I was wondering about that . . . I seemed to recall that the actuator was fitted with ball screws and end-of-travel clutches. But these are effective only if the ball nut reaches end of stroke on the screw before the flap mechanism bottoms out. > >Second, aerodynamic pressures on the flaps raise >the flap motor current significantly. To the point >That a 7 amp fuse or circuit breaker will >definitely trip. And from my experiences in multiple RV=92s I >Know that while flying, a trip can happen while >extending or retracting the flaps. > >I strongly suggest that you need to increase the >amp rating of your circuit protection to at least >10 amps. If you do that, your problems will go >away=85. All the planes listed below have had 10 Amp >Circuit protections, and did not trip during flight=85. > >Fred Stucklen >N924RV 1395 Hrs Flying >N926RV 875 Hrs Sold >N925RV 2008 Hrs Sold Thank you sir . . . good data! 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