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A bad day

N

N733JJ

Well Known Member
On Saturday I was part of a formation demo team at the EWB "Fun Day". At the end of the demo as we passed in front of the crowd, we stopped, 90 left and lead called "Smoke Now!" I hit the smoke button on my throttle as I pushed the power up to about 1700 RPM to increase the smoke volume. Despite full aft stick, in the blink of an eye, the tail rose. I chopped the power but it was too late. The momentum of the tail continued until the prop left it's signature in the taxiway. The tail then came down. Hard.

But why?!?! Simple, my flaps were still full down. If you have not yet seen or experienced it, the prop blast against the flaps will raise the tail of a typical (forward CG) RV-8 at around 1500 RPM even with full aft stick. I experienced this several years ago while doing an engine run but fortunately, was adding power slowly when the tail came up. On Saturday, I had momentarily forgotten the experience, didn't check flaps up prior to a quicker application of power. It was all over in an instant. Prop destroyed, engine to be torn down. The force of the tail coming down also put a bow in the tail spring so that will have to be replaced.

No injuries other than my pride and wallet.

It has since come to my attention that this is not a well known phenomenon so I post here to warn all, maybe prevent it from happening to someone else. Check flaps prior to advancing power above a low idle!!! If you feel that I have possibly saved you from a similar incident, the customary 5% contribution is appreciated. ;-)
 
Totally sucks, Scott. I feel for you, buddy, and applaud your posting it here for others to learn from.

However, because I read about it first on FB, I think I'm off the hook for sending you the 5%. Sorry, man. :D

Do keep us posted on your rebuild process. If you lived closer, I'd gladly lend a hand.
 
This must be very dangerous on go-arounds, or does the extra airspeed of flight prevent the nose-down tendency? Just doesn't seem right that merely full flaps could cause such a bad outcome.
 
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Buggsy2 said:
This must be very dangerous on go-arounds, or does the extra airspeed of flight prevent the nose-down tendency? Just doesn't seem right that merely full flaps could cause such a bad outcome.
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Full flaps, and locked brakes are the problem here-----and full throttle.
 
Day

OUCH! I've never experienced it, thankfully!

I never run my engine over 1700 rpm on the ground. I had read about the -8's ability to pull itself over on it's nose when I was building.

I hate those dings in the wallet. Since I've retired, (insert political statement here) my wallet isn't as thick as it used to be.:eek:
 
Thanks for posting! Something I will keep in mind in the coming years as I transition to taildraggers. I feel your pain, a simple mistake can be very costly. Fortunately, nobody was hurt.

I suspect you probably saved somebody from doing this same exact thing! Good for you.
 
Well, first, thanks for having the guts to say something to warn others.

Mike S said:
Full flaps, and locked brakes are the problem here-----and full throttle.
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Mike - It was only 1700rpm. However, the problem here is not the airplane.

I wish everyone participating in formation flying activities would get into a formal program and start following the standards. I do not believe they inlcude a parade turn followed by "smoke on", but I could be mistaken. If I am, I apologize.

Again, thanks for humbling yourself for the groups benefit. Lesson learned hard and I am truly sorry.
 
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Ouch!! I can feel your pain and frustration from here. Thanks for the reminder though.

Good luck with the tear down. Hopefully they won't find anything of consequence.
 
This is not a formation issue.

JonJay said:
Our insurance premiums keep going up. Fewer and fewer carriers will even cover formation activities now even with carded pilots. I wish everyone participating in formation flying activities would get into a formal program and start following the standards. I do not believe they inlcude a parade turn followed by "smoke on", but I could be mistaken. If I am, I apologize.
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Though the group is not FFI "carded" we are all trained (USAF for me) and well practiced. The smoke for the crowd is a common practice and would normally be considered the least risky part of the flight.

My point was that it takes surprisingly little power against full flaps to stand an 8 up. It can be done at less than run-up power. I know many people that make a short run-up at the end of a flight, often leaning to burn off any carbon buildup. This is also often done prior to a compression check at the condition inspection. Both of these situations must be approached carefully and, obviously, flaps up.
 
I have a friend who flies a biplane with a big engine. He has to do his mag checks with dragging brakes instead of locking them because the tail would come up...even with no flaps.
 
Not long ago I watched as a non-RV taildragger nosed over with the prop striking the pavement. That was inadvertently closer to full power and likely with brakes on. It is not a fun event to watch especially when it happens so quickly and being 30-40 feet away I had zero chance to help.

I wonder if this type incident is as common as A model tipovers.
 
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N733JJ said:
Though the group is not FFI "carded" we are all trained (USAF for me) and well practiced. The smoke for the crowd is a common practice and would normally be considered the least risky part of the flight.

My point was that it takes surprisingly little power against full flaps to stand an 8 up. It can be done at less than run-up power. I know many people that make a short run-up at the end of a flight, often leaning to burn off any carbon buildup. This is also often done prior to a compression check at the condition inspection. Both of these situations must be approached carefully and, obviously, flaps up.
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Fair enough. Again, really sorry for the hard lesson, but thanks. It reinforces the respect we all should have for these machines during any part of our flying activities.
 
Scott, thanks for the info...well....sort of :(

My wife isn't happy about this for 2 reasons, 1st is because she really doesn't like to see this happen to you and have JJ out of commission....the 2nd reason is because I told her how I forgot my flaps one day and took off with them down, I only noticed this after the takeoff and how "doggy" the airplane felt.

She asked me why this didn't happen to me during my runup.....

Thanks for making me tell her it was her in the back seat that gave me an AFT CG :eek:

Seriously, thanks for all the information regarding this incident, it goes a long way with us Lower time taildraggers.
 
Thanks for the story to learn from. I wouldn't be surprised if this could happen in an RV-6 or -7 too, if you had full brake and full flap and added runup power, but i'm not really all that keen to try it and find out...

Did lead forget the signal to raise flaps? :)
 
Thanks for posting this! I know a guy that did a similar stunt in phase one testing of his 7:eek:
 
Just a thought here, but I would not be surprised if part of the problem is the air spilling off the lowered flaps is so turbulent as to render the elevator mostly useless------

One would think that the arm of the elevator should be able to keep the lift vector from the flaps under control.
 
So the fact that you can't cycle the prop below about 2000RPM...How is it this accident doesn't happen a lot more on TD RV's?

Frank..7a
 
The reason you dont hear about this a lot is because not a lot of people are doing 90 degree turns in the middle of their run up...I'm not saying you shouldnt do it. It does make for a nice air show. BUT the forward momentum you generate during a turn PLUS the added power, PLUS the sudden brake application to stop at 90 degrees turns a simple run up into a prop strike. While it wasnt inattention that brought on this strike, its very similar to the red bull strike posted earlier ie, sudden stop + power on.
 
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I am fairly new to the RV world, so forgive a newbie question.

Almost every time I see pictures of an RV on the ground, the flaps are down. They look fully down as well. Doesn't seem to matter if the plane is parked or taxiing, the flaps are down.

Why is that? Every other plane with flaps I have flown has raising the flaps on the after landing checklist. I remember many moons ago when first flying Cherokees I was taught not to taxi with flaps down to avoid FOD on the flaps from prop blast.

No judgement here, just curious.
 
Flaps Down

N355DW said:
I am fairly new to the RV world, so forgive a newbie question.

Almost every time I see pictures of an RV on the ground, the flaps are down. They look fully down as well. Doesn't seem to matter if the plane is parked or taxiing, the flaps are down.

Why is that? Every other plane with flaps I have flown has raising the flaps on the after landing checklist. I remember many moons ago when first flying Cherokees I was taught not to taxi with flaps down to avoid FOD on the flaps from prop blast.

No judgement here, just curious.
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The flaps are down on most RV's that are parked to keep Newbies from stepping on the flap when they are climbing up or down on the wing.......sorry couldn't resist. It actually does help because the flap "gets out of the way" a bit when down. Checklist stuff.
 
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Can't blame "Boss"

Snowflake said:
i'm not really all that keen to try it and find out...

Did lead forget the signal to raise flaps? :)
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If anyone decides to try it on their plane, tie down the tail so it can only come up an inch!

"Boss" was a SU-27, no flaps. #2 was an RV-8 but he landed with 1/2 flaps. Now, before anyone talks about mixed type formations, yes, we all know it is riskier. We have flown together many times, know and respect the performance differences and were well briefed.

Boss was not at fault, the formation was not at fault. A very short lapse in memory/judgement on my part was at fault.
 
Chris Hill said:
The reason you dont hear about this a lot is because not a lot of people are doing 90 degree turns in the middle of their run up...I'm not saying you shouldnt do it. It does make for a nice air show. BUT the forward momentum you generate during a turn PLUS the added power, PLUS the sudden brake application to stop at 90 degrees turns a simple run up into a prop strike. While it wasnt inattention that brought on this strike, its very similar to the red bull strike posted earlier ie, sudden stop + power on.
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The turn was complete, the plane at a complete stop prior to advancing the power.
 
N355DW said:
Almost every time I see pictures of an RV on the ground, the flaps are down. They look fully down as well. Doesn't seem to matter if the plane is parked or taxiing, the flaps are down.
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We all park flaps down to aid in entry and exit from the plane... The flap isn't something you want to step on, so lowering it makes the reach from the ground to the wing-walk easier.

Why is that? Every other plane with flaps I have flown has raising the flaps on the after landing checklist. I remember many moons ago when first flying Cherokees I was taught not to taxi with flaps down to avoid FOD on the flaps from prop blast.
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SOP around here is to raise flaps before ground manoeuvering, to avoid tagging a taxiway light with them. Some days I even raise the aileron on the side closest to the edge just to be sure. When I learned to fly, in Cessnas, we were taught to raise flaps so we could look out towards the rear and still be able to see... FOD was never mentioned.

Whatever the reason, the result is that we're all taught to do it this way, and it looks wrong somehow when you see someone taxiing with them down. At least it does to me. Not a judgement on the original poster, I know I've forgotten mine too from time to time!
 
SOP's

Wind was light, not a factor in my opinion.

When I started flying my RV, I raised the flaps after exiting the runway. Over time, I decided that the risk of FOD to the flaps while in an idle power taxi was minimal and decided like most RV'ers to leave them down instead of running them up then back down to exit the plane. I do bring them up when on grass fields.

I will be reconsidering this in an effort to keep everything standard.
 
N733JJ said:
Wind was light, not a factor in my opinion.

When I started flying my RV, I raised the flaps after exiting the runway. Over time, I decided that the risk of FOD to the flaps while in an idle power taxi was minimal and decided like most RV'ers to leave them down instead of running them up then back down to exit the plane. I do bring them up when on grass fields.

I will be reconsidering this in an effort to keep everything standard.
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I too have observed a large portion of RV pilots taxiing with flaps down. I don't understand this since it is contrary to what we were taught in primary training and what is customary for other aircraft.

In my opinion....it is much better to raise flaps once the landing is complete (for taildraggers, retracting flaps may in fact be part of the landing process) and then lower flaps once the plane is parked prior to exiting the plane.
 
Having been a member of the "Bent Metal Club" a couple of times I feel your pain. :eek:

Thanks for starting the thread so others are aware. It's never easy to admit we make mistakes, but to want to help others avoid the same thing... you are to be commended. :D
 
Perhaps someone should test susceptibility to nose over in various RV taildraggers. Of course they need to have suitable safeguards to just identify the situations where it may occur yet prevent damage to the aircraft.

I know that when I see RV guys doing a higher speed runup on a new aircraft I often stand at the tail to keep it from going up. The odd thing is that I am usually the only person who thinks about it.
 
eisnerrv4 said:
I'm just curious if anybody knows if this can happen to a 4.
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Yes, it can happen in a 4, any RV and likely any taildragger. The only question is how much power is required and that will vary with the CG and it's relationship to the main gear. The RV-8 by design has a forward CG when solo so it takes very little power to upset.
 
RV-4 Run up

Thanks, this is really good to know. I have 34 hours only on my 4 and always do a run up with flaps up. Looks like I will continue to do this.

Always great to learn from the RV community, lots of knowledge out there.

Thanks again

Brian Eisner
RV4 C-GRJT
Bedford Nova Scotia
Canada
 
Thanks!

Thanks for sharing this painful lesson so others aren't doomed to repeat it. I had no idea that could happen. All it would take is forgetting to retract the flaps prior to run up.
 
Scott, sorry to hear of this - but we all learn because you shared. Hope you get fixed and back in the skies before too long.
 
Another habit pattern that might help is to always advance the throttle VERY slowly for your runup. Perhaps you could feel the tail getting light and realize something might be wrong.

There is rarely a need to add power quickly on the ground.
 
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