Archer crosswind component and slips

C

clestudentpilot

Well-Known Member
I have a question (well actually 2) and I thought this would be the most appropriate category to ask them in. I have recently started flying a PA-28-180 Archer, and was asked two questions on the "renters checkout" quiz that I can't find the answers to. The first being the maximum crosswind component. I found on AOPA's website an article that it is 17kts, which is what I was thinking, but I could not confirm that in the POH. Does anyone know where to locate that info in the POH? I have read through the entire thing, and cannot find it. The second question relates to slip to landings and limitations on them. My quess is there are not limitations based on the fact that it is a low wing. I know in the 172 you can't do a forward slip with more than 10 degrees of flaps, but I would guess this does not apply to the Archer. Again, I could not find this info in the POH. Any help in locating this info would be appreciated. Also, please tell me where this info can be found, since I can't find it anywhere.
 
17 kts is correct.

It can be found in Section 2, Limitations -- It's one of the required placards in view of the pilot.

Also in Section 4.3, Airspeeds for Safe Operation -- item (f).
 
OhioStatePilot said:
17 kts is correct.

It can be found in Section 2, Limitations -- It's one of the required placards in view of the pilot.

Also in Section 4.3, Airspeeds for Safe Operation -- item (f).
Click to expand...

Does this mean it is a placarded limitation? I thought that demonstrated crosswind components were advisory and simply represented the highest crosswind demonstrated during certification by that airplane or a similar model.

A small aside, the 172 placard "avoid slips with flaps extended" is not an absolute limitation. Slips are to be avoided. Here is a snippet plagarized from the book "Cessna, Wings for the World" written by
William D. Thompson, an Engineering Test Pilot and later Manager of Flight Test and Aerodynamics at the Cessna Aircraft Co.


With the advent of the large slotted flaps in the C-170, C-180, and C-172 we encountered a nose down pitch in forward slips with the wing flaps deflected. In some cases it was severe enough to lift the pilot against
his seat belt if he was slow in checking the motion. For this reason a caution note was placed in most of the owner's manuals under "Landings" reading "Slips should be avoided with flap settings greater than 30° due
to a downward pitch encountered under certain combinations of airspeed, side-slip angle, and center of gravity loadings". Since wing-low drift correction in cross-wind landings is normally performed with a minimum
flap setting (for better rudder control) this limitation did not apply to that maneuver. The cause of the pitching motion is the transition of a strong wing downwash over the tail in straight flight to a lessened
downwash angle over part of the horizontal tail caused by the influence of a relative "upwash increment" from
the upturned aileron in slipping flight. Although not stated in the owner's manuals, we privately
encouraged flight instructors to explore these effects at high altitude, and to pass on the information to their students.

This phenomenon was elusive and sometimes hard to duplicate, but it was thought that a pilot should be aware of its existence and know how to counter-act it if it occurs close to the ground.

When the larger dorsal fin was adopted in the 1972 C-172L, this side-slip pitch phenomenon was eliminated, but the cautionary placard was retained. In the higher-powered C-172P and C-R172 the placard was applicable to a
mild pitch "pumping" motion resulting from flap outboard-end vortex impingement on the horizontal tail at some combinations of side-slip angle, power, and airspeed.
 
clestudentpilot said:
I know in the 172 you can't do a forward slip with more than 10 degrees of flaps, but I would guess this does not apply to the Archer.
Click to expand...


WRONG! I wish people would get this out of their heads! NO WHERE does it say a slip is prohibited in a 172. Re-read your POH and your placards. It says "Slips Not Recommended with Flaps Extended." It says nowhere in the POH about a 10 deg. variation.

The only thing you have to watch out for when doing a slip with flaps extended in a 172 (and a 150 for that matter), is the pitch oscillations you will get due to the disturbed airflow over the stab/elevator. If you feel the yoke starting to pulsate or the plane doing un-commanded pitch variations, you are slipping too hard, and are at risk of "pitch-poling" the airplane.

There is a very distinct difference between "Not Recommended" and "Prohibited"
 
OK, thanks, I though it was 17 kts, but couldn't find it. I actually still can't find it. The POH I have is not actually a POH, just an Information Manual, but essentially the same info is in it. The limitation placards are in section 3, but there is nothing about the crosswind component listed. Section 4 in my manual is Emergency Procedures. Also, in section 7, Operating Procedures, I cannot find any of this info. Also, thank you mshunter. I had always been told that, and pretty much just took it for a fact, without actually verifying it. I had always been told not to do a forward slip with more than 10 degrees of flaps, because it could disrupt the airflow over the tail, and inadvertantly cause an elevator stall. I guess this must not be correct?
 
I now have looked it up and see in the 172 POH, for a 1973 M model, it says on pg. 2-16 "Steep slips should be avoided with flap settings greater than 20 degrees due to a slight tendency for the elevator to oscillate under certain combinations or airspeed, sideslip angle, and center of gravity loadings." I stand corrected, thank you. When you say "pitch-poling" what exactly do you mean?
 
Piper produce notoriously poor POHs.

Standardization doesn't exist, and I guess they figured the info was optional.
 
It's in section 2 - limitations (max Xwind). Wait until you have to get info from a Warrior I or II manual :panic:
 
Section 2 in mine is Airplane and Systems. I looked throughout limitations (which is in section 3 in mine), and there is no mention of crosswind limitations, or slipping limitations. I know this manual is for the A/C I am flying, because it lists at the beginning the serial numbers that apply to this manual, and the A/C I am flying is in the serial number range. Hmmm, well, anyways, can anyone at least tell me if slips are approved, and if there are any limits or recommendations placed on them?
 
Hey, sorry -- I got mine from the Archer II manual, YMMV.

Regarding the placard, just to clarify, the manual calls for a placard saying something like, "Maximum Demonstrated Crosswind Component -- 17 kts". The way I take that, is that the placard must be there (assuming it has an associated part number), but nonetheless, the 17 kt crosswind component is still a recommendation, not a limitation.

Just be wary of §91.13... ;)
 
Right, I understand that, and I think you were replying to the other person who replied there. I know that you can do it in whatever you want to do it in, but if the NTSB or FAA gets involved in something, and the x-wind component is 18, you're screwed. Unfortunately, I still can't find anything in the manual for it. Oh well, 17 it is and I guess there are no limits on the slips, although I still can't find any info on that
 
clestudentpilot said:
I now have looked it up and see in the 172 POH, for a 1973 M model, it says on pg. 2-16 "Steep slips should be avoided with flap settings greater than 20 degrees due to a slight tendency for the elevator to oscillate under certain combinations or airspeed, sideslip angle, and center of gravity loadings." I stand corrected, thank you. When you say "pitch-poling" what exactly do you mean?
Click to expand...


I suggest you get up to a safe altitude and experince it for yourself. You will feel a "pumping" of the elevator pressure, and at that point you are pushing the elevator too hard. It's a non event really, but something that should be felt by everyone who fly's a 172. I have only ever felt it in 172's that get the full 40 of flaps. I personally have never pushed it farther than the "pump" because of knowing what is comming next.
 
That's true, although I don't recall a specific limitation for the Archer or Warrior, but I was cautioned of that by instructors. Beyond that, I don't recall a specific time limitation for slips in the Archer, nor could I find it in the manual, but I know that other low wings do have those limitations.

Oh, and yes, I was responding to twdeckard's comment on the placard!
 
tgrayson said:
Many Pipers have a time limitation on slips, something like 20 seconds, due to the potential for fuel unporting.
Click to expand...

Prolongued slips or skids which result in excess of 2000ft alt loss (or any other radical or extreme maneuvers) - Sect 10 Operating Tips (Archer/Warrior/Arrow II's)
 
Ah, thank you, Operating Tips are in Section 8 for me, and I now see #8 in Section 8 the last thing mentioned is "Prolonged slips or skids in any pitch attitude or other unusual maneuvers which could cause uncovering of the fuel outlet must be avoided when tank being used is not full". I guess that is all the is mentioned on that. Thanks for the help guys. I still have not seen anything in the manual about x-wind, but I will just say 17, since people on here, and a few other sources online have said 17.

mshunter, I may end up doing that, although I think just to play it safe I will go up with an instructor. My question is, when you say you know what is coming next, are you refering to an elevator stall? I guess I'm just assuming this is the case, because my instructor told me another instructor at the airport took a 172 up to a fairly safe altitude, and was able to get an elevator stall, and I believe he said that he slipped it with full flaps to do it, and said that it was a very violent stall. Now I don't have any experience with this, I just took his word for it, and it is something I don't care to experience (the elevator stall I mean)
 
unclenobby said:
Prolongued slips or skids which result in excess of 2000ft alt loss (or any other radical or extreme maneuvers) - Sect 10 Operating Tips (Archer/Warrior/Arrow II's)
Click to expand...

Good catch... I completely missed that in both of mine (Archer II/Warrior II), but it was there.
 
mshunter said:
WRONG! I wish people would get this out of their heads! NO WHERE does it say a slip is prohibited in a 172. Re-read your POH and your placards. It says "Slips Not Recommended with Flaps Extended." It says nowhere in the POH about a 10 deg. variation.

The only thing you have to watch out for when doing a slip with flaps extended in a 172 (and a 150 for that matter), is the pitch oscillations you will get due to the disturbed airflow over the stab/elevator. If you feel the yoke starting to pulsate or the plane doing un-commanded pitch variations, you are slipping too hard, and are at risk of "pitch-poling" the airplane.

There is a very distinct difference between "Not Recommended" and "Prohibited"
Click to expand...
First, you are correct that it is not a limitation. I've seen "avoid prolonged slips with flap extended" placards, but the manual says the plane remains controllable.

Now is it a good practice to have these pitch oscillations? I think a good landing follows a good approach, and if I screwed up that bad, I think I would just take it around. That is, unless there was a real compelling need to get on the ground right away.

I know a guy that busted his part 141 CFI initial checkride at American Fylers. He was inbound on approach with 30 degrees flaps and the examiner asked if he could demonstrate a slip. He does so and the examiner busts him for it and has him read the placard. Fair, eh I don't think so, but with some the distinction is not that big, and they would err on the side of caution.
 
granlistillo said:
He does so and the examiner busts him for it and has him read the placard. Fair, eh I don't think so, but with some the distinction is not that big, and they would err on the side of caution.
Click to expand...

I don't generally agree with tailoring one's instruction to match the ignorance of someone else. The only people that can really police the examiners are the instructors, and for us to put up with that sort of behavior from examiners tends to encourage it. The instructor in that instance should have gone to the examiner's POI and expressed dissatisfaction not only with the examiner's expertise but also his integrity.
 
clestudentpilot said:
Ah, thank you, Operating Tips are in Section 8 for me, and I now see #8 in Section 8 the last thing mentioned is "Prolonged slips or skids in any pitch attitude or other unusual maneuvers which could cause uncovering of the fuel outlet must be avoided when tank being used is not full". I guess that is all the is mentioned on that. Thanks for the help guys. I still have not seen anything in the manual about x-wind, but I will just say 17, since people on here, and a few other sources online have said 17.

mshunter, I may end up doing that, although I think just to play it safe I will go up with an instructor. My question is, when you say you know what is coming next, are you refering to an elevator stall? I guess I'm just assuming this is the case, because my instructor told me another instructor at the airport took a 172 up to a fairly safe altitude, and was able to get an elevator stall, and I believe he said that he slipped it with full flaps to do it, and said that it was a very violent stall. Now I don't have any experience with this, I just took his word for it, and it is something I don't care to experience (the elevator stall I mean)
Click to expand...


Yep, it is an elevator stall, because you loose all tail down force, which causes you to basically be plasterd to the roof of the airplane if you seat belt isn't tight enough. I have come out of my seat do to the pitching down moment, but only at altitude. I haven't forced the issue at lower altitudes. Just curious, if you going to do it with an instructor, are you going to find one that has done this? If not, I'd be carefull to not take one that is going to "willy nilly" put the airplane in a situation where they panic. Bottom line, if you do it at a safe altitude, and know how to recover it is completely safe. I don't know about the Piper series, but the 172 series says in the Limitations section that you stress the airplane to 1.76 -g's (with 150% fudge factor). So just make certian that you do it as slow as possible.
 
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