Frailties of the 172?

[jsbrewster1]

Hi all,

Loving flying the A2A as always, but I just had an odd mechanical issue crop up again after only 138 flight hours, my left flap shows that parts are wearing out. Is this just a quirk of my particular aircraft, or are Cessnas prone to having flap issues? Or is this a random thing with A2A? Any insights would be appreciated.

Regards,

[Oracle427]

My flight school had 3 172s that they purchased brand new from the dealer on the field. 2 have had engines replaced and another was sold to another flight school. I have never heard of flap issues with them and there are no ADs for flap issues that I am aware of.

There is a 36 year old 172 that had a flap motor failure, but after 36 years and 11,000 hours, that's pretty darn good! The tracks do have wear limits, but even on this same high time airplane which is now close to 13,000 hours the tracks are still within wear limits.

The typical damage I see on flaps are dents from rocks.

I've also seen photos of flap pushrods being bent from flaps being extended at too high an airspeed. I think these things are pretty solid components.

[Lewis - A2A]

It could be everything you have mentioned in the post and remember its also dependent on how you fly (the conditions in which you fly) too which adds another element to the dynamic randomness.

thanks,
Lewis

[jsbrewster1]

Thanks for the quick replies. So I get the feeling this is just some randomness creeping in. It's possible it was the other flap that had the issue before, I forgot to specify which flap in my previous log entry, though I remember it in my head being the left flap as well. But it sounds like overall it's not something I need to concern myself with overmuch.

Regards,

[Lewis - A2A]

How are you flying her, are you extending a bit too fast and whilst extended getting a bit fast or aggressive in turns etc?

[jsbrewster1]

I don't think I've oversped the flaps, I try to watch that closely. I do sometimes extend to 20 or 30 right at the limit, should I wait until I've slowed down more? I have been in very very hot conditions, NW Australia in November, not sure if that plays into any of the issues.

[Oracle427]

By "hot" Lewis is referring to the airspeed being too fast.

I would use some caution about rapidly extending the flaps from 0 to 30 degrees right at the beginning of the white arc. even 10 degrees generates a very pronounced effect in pitch and the aircraft slows down on its own quite a bit after flap extension. The flaps are not airbrakes so don't throw them out to slow the airplane down. Better to slow down and then extend the flaps to maintain speed in the descent on final.

[jsbrewster1]

I only extend 10 degrees initially, usually around 100 knots, then let the nose rise a bit, bleed off airspeed down to around 80, then hit 20 and 30 together. Is there a better technique?

[Oracle427]

For a rectangular pattern
10 degrees abeam the touchdown point reduce power to 1500 RPM (less than 110 KIAS and slow down to 75 KIAS)
20 degrees on base (slowing 70-65 KIAS) further reduce and adjust power as needed to maintain an appropriate glide angle
30 degrees on short final when reaching the runway is assured

For a straight in approach
10 degrees maintaining under 100-90 KIAS for the approach usually around 1800 RPM.
Within about 1-2 miles reduce power and slow down into the white arc and extend to 20 degrees and continue slowing to 65 KIAS.
Once reaching the runway is assured extend to 30.

At each step prior to extending additional flaps I just hold a little back pressure and take out some power, the airspeed comes off and then I put out a notch of flaps. The additional flaps will allow me to lower the nose again and hold my new target airspeed. I am not holding the nose down and dropping out the flaps and letting them do the job of slowing the airplane down.

You can feel the whole airframe trembling a bit when the flaps are fully extended at the higher end of the white arc. I imagine that is putting some strain on the flaps though I have no idea how much wear it causes.

[jsbrewster1]

Ah, there's probably part of the problem, I've been extending to 30 way too far out... and then wonder why it takes me forever to get to the runway:) I'll try your technique tonight when I get to Tupang. Thanks!

[jsbrewster1]

Thanks, Oracle! I've been using your technique for the last couple of flights, and in addition to not tearing up my flaps, I'm much more stable on final when I've already slowed before extending them. Still having issues with my landing picture, but that's a whole other thing. Thanks again!

[Oracle427]

Glad to hear it helped!

[Lewis - A2A]

Great, yes it sounds like your technique was building and building each flight to cause the earlier wear.

thanks,
Lewis

[jsbrewster1]

Agreed, hopefully this will keep her happier for the rest of the trip around the globe))

[jsbrewster1]

Oh, one other... oddity, though I've come to expect it. After I change the oil, I generally get a message after the next flight telling me I have oil leaks. I assume I'd check the lines when I change the oil. Should I repair them when I do the oil change to reflect the inspection, random tightening, etc.? Or is it a separate issue? And I do change the filter each time I do an oil change.

Thanks,