Flap Failure Accuracy

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Avio
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Flap Failure Accuracy

Post by Avio »

Just gotten back to flying the amazing Comanche after a long break. Well the first flight went bad, as I had left the flaps in full down after preflight. Upon taking off, the left flap broke (fixed that later in maintenance), and the plane immediately went into a severe right bank and crashed.

But if the left flap broke, shouldn't the plane bank left instead of right? There was much lift from the right wing from the still extended right flap. Anyone else observed this? Is this a bug?

On another subject, in the Comanche for ILS tuned in, there is no DME distance picked up. Is that right too? Was tracking the KRDD ILS.

Any advice much appreciated.

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Scott - A2A
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Re: Flap Failure Accuracy

Post by Scott - A2A »

I will need to test this. It's possible something got reversed.

Scott
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Avio
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Re: Flap Failure Accuracy

Post by Avio »

Thanks Scott. Hear from you again then.

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AKar
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Re: Flap Failure Accuracy

Post by AKar »

Avio wrote: 16 Nov 2021, 07:28 On another subject, in the Comanche for ILS tuned in, there is no DME distance picked up. Is that right too? Was tracking the KRDD ILS.
May be worth checking out if the scenery you are using has an ILS set up and on the correct frequency. Checking for the correct terminal navaids is something I do whenever I first fly to or from a specific airport in the sim. As well if using scenery addon, as many tend to get these wrong.

-Esa

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DHenriques_
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Re: Flap Failure Accuracy

Post by DHenriques_ »

Avio wrote: 16 Nov 2021, 07:28 Just gotten back to flying the amazing Comanche after a long break. Well the first flight went bad, as I had left the flaps in full down after preflight. Upon taking off, the left flap broke (fixed that later in maintenance), and the plane immediately went into a severe right bank and crashed.

But if the left flap broke, shouldn't the plane bank left instead of right? There was much lift from the right wing from the still extended right flap. Anyone else observed this? Is this a bug?

On another subject, in the Comanche for ILS tuned in, there is no DME distance picked up. Is that right too? Was tracking the KRDD ILS.

Any advice much appreciated.
About the flap failure;

Without actually having seen the exact circumstances...............

IF the left flap linkage failed and the flap went into trail with the wing.........AND the right flap was locked full down, the right side flap would be well into its drag rise range and for all practical purposes beyond the point where lift being produced could overcome the drag rise.
In this case the right wing could well drag the wing down into a right side departure.
It all depends on EXACTLY where ALL the physics is in play at the EXACT moment the left flap linkage fails.
So chalk it up to a "possible" occurrence. Accusim programming is quite complex concerning the physics. If the angle of attack is just right and the airspeed is just right...........what you have described could happen.
Dudley Henriques

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Scott - A2A
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Re: Flap Failure Accuracy

Post by Scott - A2A »

Yes Dudley is correct. Do you remember if the flap broke or jammed? Because if it broke and your other flap was still deployed then the behavior would be correct. You would know this because once on the ground the broken flap would be hanging down from gravity. It's only when you get up to speed where the wind lifts the flap where it would appear up, or close to up.

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Avio
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Re: Flap Failure Accuracy

Post by Avio »

Thanks a lot for the advice, folks.

For the ILS, I shall try it again on another airport to see if it picks up the DME.

As for the flap failure, I did another flight (after fixing the left flap with a fresh set) with a much worn out right flap, intentionally taking off with full flaps down (like in the earlier incident). True enough, the right flap failed, and the plane went into a steep right bank and crashing.

Did a check prior to fixing that, and the right flap was hanging loose, clearly broken. In this case, the resulting action seems correct given the lift from the left still down flap, although it must had been also causing lots of drag too.

For the earlier left flap failure, I had overlooked to check on whether it was a broken or jammed flap prior to fixing, though I suspect it could be a broken flap too as the resulting severe bank and crash was exactly the same, but on the side that was not expected.

By the way, for the second case of right flap failure, looking at the pre-flight linkages picture, no abnormality was shown. Isn't the broken link supposed to show up? Or is the picture just a static display for whatever state the linkages may be in? Or does it show loosened linkages, missing nuts, etc., with continued usage over time?

Avio
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Re: Flap Failure Accuracy

Post by Avio »

About the Accusim programming as quoted by Dudley, does it simulate to a close degree as done using blade element modelling, as used by DCS and X-Plane? If so, that would be really a genius piece of work, given the need to work around FSX inherent constraints.

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