What does the POH say about flap settings?

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ScudRunner-d95
Posts: 1349
Joined: Thu Feb 13, 2014 5:08 pm

No POH I ever read said NOT to crash the plane anywhere.....


Trey Kule
Posts: 250
Joined: Tue Aug 09, 2016 4:19 am

Well then,  if the POH does not specifically state you are not to crash, feel free to experiment. Let us know how it works out for you.

As to my original post. And subsequent . I was specifically not asking about x-winds.  Though I am not sure what difference that would really make.
Some of the logic I find a bit unusual, but that just might be me.
John Swallow
Posts: 319
Joined: Fri Jun 03, 2016 1:58 pm

Although I in the "Full Flap" crowd because of the aircraft I have flown (even my present ride), I found some interesting info at the following link:

http://commons.erau.edu/cgi/viewcontent ... text=jaaer

It's a little dated, but I think the study is still valid...
JW Scud
Posts: 252
Joined: Sun Aug 14, 2016 12:44 am

[quote author=Trey Kule link=topic=5846.msg15399#msg15399 date=1489869736]
Well then,  if the POH does not specifically state you are not to crash, feel free to experiment. Let us know how it works out for you.

As to my original post. And subsequent . I was specifically not asking about x-winds.  Though I am not sure what difference that would really make.
Some of the logic I find a bit unusual, but that just might be me.
[/quote]


True, I re-read your post and obviously, I did not read it thoroughly(a bad habit that could be dangerous in the piloting world). You mentioned winds, not strong crosswinds. There can be a large number of different situations for "winds" but more often than not, I would plan on using full flaps unless there is some other consideration to not do so, of which there can be many. Therefore, it would seem logical for the instructor to teach full flap and partial flap landings.

Trey Kule
Posts: 250
Joined: Tue Aug 09, 2016 4:19 am

John , that was an excellent read...

I found it interesting that as a Mooney was referenced here, it was also mentioned in the article (20J)
David MacRay
Posts: 1259
Joined: Wed Jun 03, 2015 3:00 pm

I know you did not ask and I was already a bad personâ„¢ for posting about cross winds, but since the Colonel is too busy at the beach with his chapped lips..

I noticed something interesting while snooping through my skyhawk INFORMATION MANUAL looking for stuff about flaps and winds.

I noticed it mentioned in the notes above the performance chart. And I quote, "For operation with [b]tailwinds[/b] up to 10 knots, increase distances by 10% for each 2 knots."

Oh mien goodness gracious!
Tailwinds!eleventy! Don't panic but...
TAILWINDS
[u]tailwinds[/u]
[move]tailwinds[/move]
Up to 10 knots? I think a FTU 172 broke just from me posting that. Won't someone think about the flight instructors?
Chuck Ellsworth

Excellent post Shiny. :)
JW Scud
Posts: 252
Joined: Sun Aug 14, 2016 12:44 am


[quote author=Shiny link=topic=5846.msg15473#msg15473 date=1490042884]


I think he was referring to TK's initial sample of "very experienced pilots" that sparked the discussion as opposed to the present company of "very experienced pilots".

Either way, as a note of language, the later model of 172s wording of avoiding slips with flaps extended, is almost unique in all the AFMs and POHs I have collected over the years. In part my response here was delayed to do my research so to speak. In no other instance does the language "avoid" or "does not recommend" appear where an manufacturer wants to prohibit something. Its always the strongly worded "PROHIBITED" usually followed by the "failure to observe may result in bodily injury or DEATH". I also say later model 172 since the "avoidance" recommendation is absent from the pilot operating pamphlet that I have for my square tail 172, as is the placards. Notably as well its absent from the other exceedingly similar and evolutionary models of Cessna. 182s and 150/152s have no such recommendations.

On a point of detail, if the manual says to avoid slips with flaps extended, then logically if one may have to slip to conduct a crosswind landing then one could say that you should also avoid crosswind landings with flaps. Maybe the manual needs to be even more pages to state that explicitly, it seems to have gained a lot of pages over the years, and my personal opinion is the "flap avoidance" recommendation is in there because too many neophytes are freaked out by the oscillation that may be produced, and the language in the POH saves a lot of trouble on the manufacturer's side of owners trying to have problem fixed or blaming accidents on the airplane rather than their lack of skill.
[/quote]

I thought that I might post something here from another forum in the interest of safety as it is about this very subject.

"Cessna engineering test pilot and flight test/aerodynamics manager W.D. Thompson, author of Cessna: Wings for the World (pg.41) discussed the problem as late as the 1972 Cessna 172-L model, and he mentions that it applied to all 170, 180, and 172 aircraft up to that model. He mentions that in some instances the problem was severe enough to lift the pilot against the seat-belt!
Cessna vertical and horizontal stabilizers were given increased span/height to decrease the problem, but he states "we privately encouraged flight instructors to explore these effects at high altitude, and to pass on the information to their students. The phenomenon was elusive and sometimes hard to duplicate...."
Even after larger tail surfaces were installed there still was experienced a "mild, pitch 'pumping' motion resulting from flap outboard-end vortex impingement on the horizontal tail at some combinations of side-slip..."

The phenomenon only occurs at flap settings greater than 30-degrees, and later airplanes were limited to that flap setting for several reasons (including balked-landing-climb certification climb requirements and to reduce stresses placed upon the rear door-post as gross weights were increased) which made the warning become moot.
Unfortunately, pilots who gain their experience in later airplane models (and even some long-time/experienced owners of 170B and 172 aircraft will argue against the warning as rumor.) "

Remember, just because you can get away with something in one version of a particular aircraft type doesn't mean that you can get away with it in other versions of the same type.

Make sure that those so-called "experts" out there are actually experts on your particular aircraft type.
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