Flaps during pre-flight

[will1874]

My POH makes no mention of extending flaps for a pre-flight inspection. Does anyone do it? Any reason NOT to do it?

[201er]

2 minutes ago, will1874 said:

My POH makes no mention of extending flaps for a pre-flight inspection. Does anyone do it? Any reason NOT to do it?

Yeah, cause if they’re not coming out for takeoff, you’ll probably catch it then. Most M20Js have flap hinge covers. There isn’t much you can see anyway and not much visible difference between extended or not. Just visually confirm they come down when set for takeoff.

[toto]

16 minutes ago, will1874 said:

My POH makes no mention of extending flaps for a pre-flight inspection. Does anyone do it? Any reason NOT to do it?

I’ve heard the following argument against testing flaps during preflight:

If you can land the plane without flaps, but you can’t take off with full flaps, then testing them during preflight runs some risk that they’ll be stuck full down and you can’t depart. If you don’t test during preflight and they won’t come down for landing, you just land without flaps and get them fixed at your destination. 

[MikeOH]

As part of my walk-around I check the brackets and hardware on the flaps.  If they were down I wouldn't be able to do that without crawling under the wing front the front.  When I extend them before takeoff I can check for even and smooth operation.

[Culver LFA]

Yes, after my run up and mag check I extend and retract the flaps (hydraulic) as part of the control check. 

[DCarlton]

I usually lower them to the take off position when I first open the door, then give them a little tug up and down during the walk around.  Then let them up when seated and back down to takeoff before departure.  It's not based on much other than early training; it's just what I do.  I did experience inboard flap hinge corrosion many years ago and had to replace a hinge.  I think there was a service bulletin.  So yes, I exercise mine.  

Edited November 25, 2021 by DCarlton

[Oscar Avalle]

I also exercise mine. I put them in take off position and check for movement.

[philip_g]

I don't exercise them. I leave them (or bring them down to) full down after landing and bring them up to half before runup. Keeps passengers from stepping on them 

Edited November 25, 2021 by philip_g

[Shadrach]

I push mine down by hand (they’re hydraulic) to ensure they move smoothly without binding.

[Hank]

1 hour ago, Shadrach said:

I push mine down by hand (they’re hydraulic) to ensure they move smoothly without binding.

I push down on my electric flaps during preflight to ensure that they do not move.

[LANCECASPER]

I figure that they only have so many cycles in their lifespan (especially those little troublesome relays), so I'd rather not use those up by checking them twice before take-off. If they don't come down in my pre-takeoff checklist that means I won't be using them for landing and I'll be getting them fixed soon. But I would hate to scrub a trip over flaps being stuck down.

[Shadrach]

1 hour ago, Hank said:

I push down on my electric flaps during preflight to ensure that they do not move.

Unique thing about the hydraulic flaps is that they can be moved  across their full range of travel from outside the plane.  It makes it easy to verify everything is moving smoothly.

[BKlott]

If I am renting an aircraft that I am not familiar with, I check the flap operation prior to takeoff. 
 

On my own aircraft I do not check the flap operation due to the added wear and tear on the system. My feeling is that if the flaps worked properly on the last flight, they should be fine. Now, before you go wild, let me explain further. If I check the flap operation in the run-up area prior to departure and they work, that still provides no guarantee that they are going to work the next time that I come in for landing, right? How is a check in the run-up area any more predictive of future flap operation than the fact that they worked on the previous landing? The answer is….it isn’t. 
 

Things seem to work right up to the time that they stop working. Added, unnecessary operations of the flap system actually increases the likelihood that the system will fail when you NEED it to work. That is my thinking. 
 

 

[N201MKTurbo]

If the flaps were important, I would check them. About all they do is change the deck angle. 
 

Let the flames begin!

[GeeBee]

If you can take off without them and land without them, then all you are doing is checking the bulb in the fridge.

 

[DCarlton]

6 minutes ago, GeeBee said:

If you can take off without them and land without them, then all you are doing is checking the bulb in the fridge.

 

Except for the SB regarding flap hinge corrosion and the potential for structural issues.  I have the idea that if I check my flaps, I might catch a bigger problem.  I've already replaced one hinge and I've had the aircraft painted but I learned enough to make me want to check the flaps.  But I get your point.   

[RobertGary1]

On 11/25/2021 at 2:22 PM, philip_g said:

I don't exercise them. I leave them (or bring them down to) full down after landing and bring them up to half before runup. Keeps passengers from stepping on them 

The aim says that’s also the international signal for hijacking. 

[philip_g]

2 hours ago, RobertGary1 said:

The aim says that’s also the international signal for hijacking. 

Literally nobody cares 

[PT20J]

On 11/25/2021 at 5:02 PM, N201MKTurbo said:

If the flaps were important, I would check them. About all they do is change the deck angle. 
 

Let the flames begin!

The idea that Mooney flaps are not very effective comes up every so often. Given the near reverence for Al Mooney and his design prowess among Mooney owners, it always amazes me that some think Al would design useless flaps. Perhaps the misunderstanding comes from experience in Cessnas with the significant drag created by those flaps when deflected 40 degrees. The Mooney is a much lower drag design and the Mooney flaps do not add the same drag increment as in a Cessna. But increased drag is not the primary function of flaps. Flaps are categorized as high lift devices and their primary function is to increase the lift coefficient at a given angle of attack thereby reducing the stall speed and allowing for slower landings. Here are some POH CAS stall speeds for comparison. The first number is the clean stall speed, the second is the full flap stall speed and the last is the delta between the two.

SR22 69/59/10

M20J 63/56/7

C-172N 50/44/6

PA28-181 58/52/6

C-182T 54/49/5

A36 64/59/5

Skip

[cliffy]

In reality how many flap system failures in flight have actually happened?

What's the worst hat can happen if they don't come down?

What's the worst that can happen if they don't go up? 

Either is fully manageable.

[EagleDriver]

1 hour ago, philip_g said:

Literally nobody cares 

Yes.  The normal reason things are published in the AIM.