How frequently do flap hinge attachments crack?

[AndreiC]

Well, I did it myself. (It seems like many people do this...) I was flying a practice instrument approach the other day, and after seeing the runway I went missed and in the process I forgot to raise the flaps. I flew for about 5 minutes with them fully deflected, and almost certainly exceeded the white arc speed when I leveled off at 3000'. By how much, I cannot tell, maybe 10-15 mph? The question I am asking is how likely it is that I may have cracked something at the flap attachment points on the subspar. 

My Mooney is a 1970 model, with the beefed up flap hinges and electric flaps. I have seen many people say they made this mistake of overspeeding the flaps, and also many people saying that they had to repair cracks in the subspar, but almost all the repairs I have seen seem to have been from people with early model Mooneys (before 1968, I believe), that needed to have the Mooney SB done. With the newer style hinges and with what I did, what is the likelihood I damaged something that needs to be looked at now, as opposed to waiting a couple of months until the annual?

 

[AndreiC]

Actually I just checked flightaware, and my ground speed on that incident never exceeded 133 mph, and that might have been after the flaps were retracted. The winds were calm that day, so my guess is that the most I exceeded the flap extension speed of 125 MIAS was by about 8 mph.  A more precise data point.

[N201MKTurbo]

You are most likely fine. If it will make you sleep better, pull the belly panel between the flaps and inspect it for cracks.

[EricJ]

+1 that I think flap hinge spar cracks come from repeated stress, not a single event.    You can find pics here somewhere of where the cracks happen, and just inspect those spots if you're sufficiently worried to take the relevant belly panel off.   I think there has been a few cases where the cracks were hiding behind the mounting hardware, so it just means a fairly close inspection may be required.    FWIW, it's the sort of thing that should be looked at every annual, anyway, but many IAs may not or may not even be aware to do so.   In any case, annual inspection is a good time to check the spar, service the flap actuator, etc.

[PT20J]

I think most of us have made that mistake a time or two if they will admit it 

There is a lot of give in the flaps at the 15 deg position and this naturally relieves some of the stress.

Technically the white arc is for full flaps -- Mooney never published a speed for partial flaps except on a few M20Js (205s I think) where it is 126 KIAS.

I wouldn't worry about it.

[N201MKTurbo]

19 minutes ago, PT20J said:

I think most of us have made that mistake a time or two if they will admit it 

That’s crazy talk! I’d never let that happen! 

[M20F]

2 hours ago, PT20J said:

I think most of us have made that mistake a time or two if they will admit it 

I admit nothing!

[Ragsf15e]

I had the famous “sticky switch” version of the hydraulic flaps, so technically I didn’t “leave” mine down, but I did fail to confirm they were up.  When I leveled off, she didn’t accelerate that fast and the attitude looked weird.  It didn’t take long to figure it out.  A little lube in the flap cable and better checking of the indicator helped.

Mine had the crack when i bought it and it was behind the mounting hardware on the stub spar as @EricJ said.  I seriously doubt you hurt anything, but I know it feels bad.