At What Speed Does Flaps Down Cause Actual Damage?

[Fatback 84]

Assuming I'm taking off with a GW of 819,000lbs with a SPD TRANS of 278 / 10000. I believe the flaps should be fully retracted by 278-20=258kts. If I had the leading edge flaps extended (Flaps 1) at 278kts on ascent would this cause structural damage? 

[cubs 2]

There are flap limits, you can over speed the flaps and cause structural damage. There is a flap limit placard next to the alt flaps switch. 

These speeds must not be exceeded. The leading edge variable camber flaps are made from a thin bendable fiberglass. when the leading edges

are retracted, they are flat and fair with the lower surface of the wing. There are eight pneumatic motors within the leading edge that drive

torque tubes that connect to gearboxes. The gear boxes are connected to the variable camber flaps by scissor links. As the leading edges

extend, they will start to camber. At the lower end of the leading edge flap is a bull nose. This becomes the leading edge of the wing.

Very interesting design. Flap limits are: Flaps 1-280KTS, 5-260 KTS, 10-240KTS, 20-230 KTS, 25-205 KTS, 30-180 KTS.

A flap load relief system operates if flap airspeed limits are exceeded with the flap lever in the 25 or 30 position.

Back to over speeding the flaps. exceeding the flap limit does not mean you damaged the aircraft. It depends on 

how much your over speed was. If it was a couple Knots, no big deal but the aircraft would still require an over speed

inspection. If the over speed was 10 Knots or more, You could do damage to the flaps. It also depends on the age of

the aircraft. Worn bearings, load rollers. composite panels ( delamination ). These devices take a beating while in the

extended position, extending them near max speed is not a good idea.  

 

 

Doug Morlan

 

 

[Fatback 84]

Doug, thanks for the detailed reply. You answered my main question and a few that were lurking in the back of my mind. Thank you!

 

rgds,

Bill

[Eric_Parker 4]

The PMDG 747-400x has flap blow-up protection. What that means is; within limits, the airplane will retract the flaps if overspeed conditions occur. Not completely but steps at a time. It is not perfect and requires a fair amount of pilot expertise. For example, you are flying at 155 KIAS and push the throttles to max and nose over. Very quickly you could exceed 200 KIAS. Don't do that.

 

Personally, I have the "destruct" features in FSX turned off. They are not realistic anyway and I got tired of having airport trucks running into my airplane, ruining all my preflight settings.

[Sponge 74]

Personally, I have the "destruct" features in FSX turned off. They are not realistic anyway and I got tired of having airport trucks running into my airplane, ruining all my preflight settings.

 

That really is SO annoying..

Couple of days ago, i did preflight and all and was ready to taxi.

I was at the UPS ramp in Philly where you don't need pushback, just go and taxi.

I started rolling and crash...

It appeared i ran over a pushtruck, wich MFSX placed directly in front of my nosewheel...

So incredibly annoying..!!