Brantel

Brantel

Well Known Member
Not sure how I missed all the post about not using a 5 amp fuse on your electric flaps but I did and my fuse blew at the worst moment it could have.

Since I am but a pup on this whole taildragger experience, I sometimes need to "go around". It is not cool when your realize too late that your electric flaps are not retracting and you must manage power, altitute and speed to get turned around and back on the ground! Expecially when you are only 5 hours into Phase I on a brand new airplane.

Apparently my fuse blew either when extending the flaps for the landing or when I tried to raise them for the go around.

All went OK but the pilot needed a break after that ordeal. I put in a 7.5 amp and flew later in the evening and all was well.

Anyway, it is nice to know that an RV7 with a O-360/FP with a DA of around 3000ft does have enough performance to climb to safe turn around altitude even with full flaps. Matter of fact you must be carefull not to exceed flap speed.
 
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Brian

Glad to hear that everything turned out ok in the end. I'm glad that you highlighted the 5 vs 7.5 amp fuse for the flaps. I missed that one also.
 
This is a very common failure mode. This has been discussed quite a bit here. The motor pulls more amps when it has air load on it. There really should be a mention of this somewhere in the manual.
 
3 amp circuit braker for me!!!

I have installed in my 8 a 3 amp circuit braker and a TCW Tech Flap Controller and works absolutely fine.
 
AirbusPilot said:
I have installed in my 8 a 3 amp circuit braker and a TCW Tech Flap Controller and works absolutely fine.
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I use the TCWTech Intelligent Flap Controller with a 5 amp breaker and have about 80 hours on my -8 and have never popped a flap breaker.
 
You could probably fly the circuit with flaps at 40 degrees without too much trouble. As you found out, the RV typically has a lot more power than it needs for takeoff. You'd need a bunch of trim, and to keep the power back to avoid overspeeding the flaps, but there's nothing wrong with flying circuits at 90-100mph. The Cessnas around you will thank you. :)
 
Maybe the 8's are different somehow in the load on the flap motor. I doubt the controller has anything to do with it unless it is some kind of magic, perpetual motion machine. :p

flickroll said:
I use the TCWTech Intelligent Flap Controller with a 5 amp breaker and have about 80 hours on my -8 and have never popped a flap breaker.
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AirbusPilot said:
I have installed in my 8 a 3 amp circuit braker and a TCW Tech Flap Controller and works absolutely fine.
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lcnmrv8r said:
Manual flaps. ;) Glad you got it back safe and sound with no issue. I've had three electric flap failures and that is essentially why I went with manual flaps.
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Can you share more about your manual flap installation? I am not a big fan of electric flaps (I owned a Cherokee).
 
lcnmrv8r said:
Manual flaps. ;) Glad you got it back safe and sound with no issue. I've had three electric flap failures and that is essentially why I went with manual flaps.
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I hate manual flaps in side by side RV's! :)

They're nothing like the flap handle in a Piper. They are squished between the seats and can be awkward, especially when there is a passenger.

I've had a failure too. Turns out the wires coming out of the motor were pulled at a too tight 90 degree angle & frayed. The fix wasn't too difficult.

In the meantime, I prefer keeping one hand on the throttle where I can easily flip the flap switch with one finger, while the other hand is on the stick.

L.Adamson --- RV6A
 
Brantel said:
Maybe the 8's are different somehow in the load on the flap motor.
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Dunno if they are different, I suspect they are about the same. Prior to the installation of the Intelligent Flap Controller, I questioned Bob Newman at TCW Tech after reading earlier threads about flap circuit breaker issues. He said that the 5 amp breaker was plenty. So far he's been right.
 
Most RV's - if not all - have plenty of power to handle a go-around with flaps extended, as you found out. In fact this is not a bad thing, because it keeps things slow and keeps you in total control. The only thing to watch out for is not to exceed the max flap speed, which means you'll have to pull some power off sooner than you may think. You may wonder what would happen if the engine quits then..... you can't glide as far. I think the difference in glide distance at this phase of flight, it would be measured in feet, not miles, and may work out for the better. Perhaps we should all try go-arounds with landing flaps extended to see how it works out. It would be about the easiest go around you could do. Just increase power, maintain airspeed, and fly the pattern. No re-configuration - twice, not as many power changes, keep a slow tight pattern.... simple.
 
breakers vs fuses

Brantel said:
Maybe the 8's are different somehow in the load on the flap motor. I doubt the controller has anything to do with it unless it is some kind of magic, perpetual motion machine. :p
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The amp rating on a fuse vs. a circuit breaker is somewhat of an apples-to-oranges comparison without looking at the product sheet. The tripping current can be several times the rated current.

That said, we have a 5 amp ATC fuse protecting the flap circuit in our RV-6 and it has never blown.

--Paul
 
apkp777 said:
Can you share more about your manual flap installation? I am not a big fan of electric flaps (I owned a Cherokee).
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Tony,

Like you, I wanted manual flaps on my -9. After calling Van's I dropped the idea. The -9's flaps are so long that they felt you might not have the strength to put them dowm.

That said, the RV-6 flap handle should fit in the -9. Try doing a search, this has come before.

Back to the topic...
In the manuaLthere is a sample electrical system which shows a 10 amp breaker on the flaps, so that's what I used.
 
I have a 5 amp breaker on my flaps. I have over 600landings and 280hrs in 10months and my flaps work great. These are some things you might want to check out.

A short- the left floor panel has a piece that goes up under and into the area of the motor, this is in the back floor. When installed it can cut into the wires for the motor. The repair that I did for this was to just cut off that piece of the floor panel and of course fix the wire.

A bind in the system- The white plastic thingy's should only be tightened to being snug. Just enough to take out any play. Anymore and you might be causeing bind.

Check your rods that go through the fuse, might be hitting the fuse at some point.

Going beyond the stops- when lowering or raising you may be letting the button stay on after you hit the stops, this will cause a load up and blow the circuit breaker.

A bad motor, causing high loads and blowing the circuit breaker.
 
Root Cause Analysis

I guess this is a good thread to highlight root cause analysis.

Brian, in another thread has described an additional problem with his static/pitot system. The ASI and the altimeter are both giving strange readings and the ASI is reportedly under reading. This may point to why the fuse popped if the flaps were extended at above VSO. Increased air loads would mean increased current required by the the flap motor to deploy the flaps. Maybe the 5A fuse is good for flap motor loads below VSO.
 
Maybe he should go to the FBO that does pitot static checks and get an IFR check out. Maybe with that check they can find the problem.
 
This discussion is in the other thread but...

While a Pitot Static check works great for checking the accuracy of your system on the ground and checks for leaks, it does nothing for checking for static position errors.

I have done the equivalent of a pitot test and a partial static test using a manometer. Can't do a full static test since I do not have a manometer big enough.


slyfox said:
Maybe he should go to the FBO that does pitot static checks and get an IFR check out. Maybe with that check they can find the problem.
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I agree 100%....I know my airspeed is reading low at this point and have adjusted my technique to ensure that I do not exceed VSO with the flaps out.

Those that have gotten away with a 5 amp fuse for years may be very good at their flap use techniques or their airspeed is off on the high side and that naturally protects them. I would say most are good with their technique.

As for those like me that popped a 5 amp fuse, they may very well have poor flap technique and have exceeded VSO or they have airspeed error similar to mine and they exceeded VSO without even knowing it.

Anyway, I am using a 7.5 and feel good about it. The 5 amp is too close to the edge for me.

islandmonkey said:
I guess this is a good thread to highlight root cause analysis.

Brian, in another thread has described an additional problem with his static/pitot system. The ASI and the altimeter are both giving strange readings and the ASI is reportedly under reading. This may point to why the fuse popped if the flaps were extended at above VSO. Increased air loads would mean increased current required by the the flap motor to deploy the flaps. Maybe the 5A fuse is good for flap motor loads below VSO.
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If you checked everything out and find no binds and no shorts, no problems on hitting the stops with button pushed here is another things to try.

Check your GPS altitude with what your Dynon shows for altitude. Mine is spot on. If you have a problem or difference than I would do this. Make sure you have a resetable breaker on the panel for the flaps. Fly and operate the flaps to find out when it pops. At that point start figuring what your problem is. If its right when your first appy the flaps than try at a lower speed. If your GPS is recording an altitude off from your Dynon I would say the first thing you need to do is fix your static system. Install the vans system or something or just mental note the problem and keep fiddleing with things until you get it fixed. But main thing, fix or mentally adjust your airspeed so you don't put the undo stress on your flaps. Putting a bigger breaker could fix the problem , but what if you have a bigger problem and you are just covering it up, ie the air speed indicator reading to low. You could loose a flap in the future and that would be bad.
 
slyfox said:
Check your GPS altitude with what your Dynon shows for altitude.
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If you go this route, make sure you're only comparing GPS and baro altitude while you're on the ground. In flight, the nature of the atmosphere will often cause GPS altitude and barometric altitude to be quite different, perfect static system or not.

mcb
 
mines always been accurate at 1000ft agl. besides what else does he have to use at this point besides another airplane flying side by side with known proper readings.
 
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Use breaker for flap motor!

I put breakers in for all the "important" stuff that you would want to be able, either shut off (f.e. run away trim), or reset ones they trip (f.e. accedently lowered flaps at a to high airspeed). So I only have fuses for lights and things like that.

I do have a 5 Amp breaker for the flaps though. Not flying yet so I can not tell if it will work or not, but I sure hope so, changing the breaker would be a real pain!

Regards, Tonny.
 
mburch said:
If you go this route, make sure you're only comparing GPS and baro altitude while you're on the ground. In flight, the nature of the atmosphere will often cause GPS altitude and barometric altitude to be quite different, perfect static system or not.
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That can & will happen...............but it think it's kind of nifty when I bring up the panel page on my Garmin 696 & reset the altimeter to what XM weather is showing on the 696............and then have the plane's altimeter & panel page altimeter exactly follow, for a while...

This just gives an indication of what WAAS can do in regards to GPS derived altitude. Trouble is, barometric pressures change.

L.Adamson --- RV6A
 
L.Adamson said:
This just gives an indication of what WAAS can do in regards to GPS derived altitude. Trouble is, barometric pressures change.
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Not just baro setting, but the lapse rate as well. This what really causes a discrepancy when you're up high, although at 1000' AGL it may not be very noticeable. Certainly up at 10,000' AGL there can be quite a difference, and I'll leave it at that to avoid hijacking this thread. :)

mcb
 
mburch said:
Not just baro setting, but the lapse rate as well. This what really causes a discrepancy when you're up high, although at 1000' AGL it may not be very noticeable. Certainly up at 10,000' AGL there can be quite a difference, and I'll leave it at that to avoid hijacking this thread. :)
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It was the laspe rate that got my attention. Although I probably wasn't climbing or descending more than 500 fpm (wasn't paying attention to the VSI), is that the Garmin 696 synthesized altimeter was just as smooth as the plane's six pac alt. I remember the 496's panel page updating faster than the 296's, and the 696's might even be faster.

Way off topic........... :)

L.Adamson -- RV6A
 
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