Adding flaps during the descent

[jesse]

A little of both. We were last at DET over a week ago but they did break us off for a Citation behind us, and asked us to keep our speed up at least one other time.

Also, at FNT we were cleared to land on 27 and then told to go around for landing traffic on 18. It's pretty much all the towered airports around here, though PTK is definitely the busiest (second in Michigan only to DTW I think).

It's also that my instructor argues that the airplane is easier to control accurately at higher airspeeds. Based on my experience so far, I can't argue with that.

I don't necessarily agree with that. It is true that the plane's response to the controls will be "crisper" and although that does make the plane feel more controllable the faster you go the faster things go awry.

I think all airplanes tend to have their own sweet spot. Push them past that sweet spot and it becomes more difficult.

Could you shoot an ILS at 115 knots in a 172? Probably. But it sure wouldn't feel right. OTOH doing it at 115 knots in a Bo would be much different.

I generally fly 90 knot approaches in a Cherokee 180 -- I can stay high and come "racing" down the approach with a lot of RPMs at the last minute -- but it sure doesn't feel that "comfortable". Mostly because one has to delay things to get that sort of speed, plus, the controls just aren't balanced for that.

 

[azure]

I don't suspect the LOM will ever be back. If you don't have IFR GPS you'll be like me and need vectors. Selfridge of your CFII should be able to help you there.

Sorry to hear that. I forget what time does Selfridge close? I don't think Cleveland Center can vector you at approach altitudes, so it sounds like returning late at night could be complicated.

We do have IFR GPS. But the Cardinal RG I flew when I was based at PHN didn't, and if I'd bought it I would be in the same boat now.

 

[RMCN172RG]

I don't get how "practice approaches" are not allowed.

Are they saying you are not allowed to go missed? If not, then how can they disallow practice approaches?

Thay are saying you are not allowed to fly over the airfield.

 

[azure]

I think all airplanes tend to have their own sweet spot. Push them past that sweet spot and it becomes more difficult.

+1

I should say that I don't necessarily agree with "faster is better" either. In the plane I train in, 110 knots is definitely harder than 90-95, but so is 75 with flaps. IME.

 

[SkyHog]

Thay are saying you are not allowed to fly over the airfield.

Edit: I'll not hijack this thread with this question, thanks for the info!

 

[poadeleted20]

But as you said, getting good at two different methods means a lot of practice with both. At PTK the slow method won't work at all, and a lot of the time it won't work at FNT either.

I'll bet that if you file IFR to either airport, the "slow" method works just fine. It's only when you're flying practice approaches VFR that it's a problem.

So why switch methods midstream when I'm most of the way toward getting it the flaps-up way?

If you can do it flaps-up including the transition to landing both on a long ILS runway and those short runways off a non-precision approach, stick with it. If not, you'll have to come up with another solution.

And I do take your point about making sure I'm comfortable with "chop and drop" before doing it for real. I'm sure my CFII won't let me give up on configuring during the descent unless I can demonstrate proficiency with the other method.

Frankly, I think you should give up on your instructor, but that's a decision for you to make.

I don't think it will be a problem though. I know that I can go from approach descent (90-95 kts) to 10* of flaps starting from 400 AGL without ballooning, and be stabilized again by 300 AGL. Why should it be any harder from 200 AGL? I wouldn't do it at VLL, but all the ILS runways around here are >= 5000 feet.

Not all approaches are ILS, and not all end up at 5000+ runways.

A nonprecision approach with a 400 AGL MDA in low weather to a wet 3000 foot runway will probably be beyond my personal minimums for a while.

If so, you're not ready for the IR practical test, because that's something you have to be able to do to be sure of passing it.

I'll definitely practice the ones around here though (typical MDAs 500-800 AGL and/or runways >=4000 feet).

I know plenty of approaches in your neck of the woods ending at much shorter runways than that.

 

[azure]

I'll bet that if you file IFR to either airport, the "slow" method works just fine. It's only when you're flying practice approaches VFR that it's a problem.

You could be right about that, I can't recall for sure if we were IFR the time they sent us around at DET for the Citation or if that was the second time, when we were VFR. But getting an IFR clearance at VLL is a pain since they decommissioned the GCO, and my CFII is against picking up a clearance airborne. I doubt if I can talk him into filing for everyday training.

If you can do it flaps-up including the transition to landing both on a long ILS runway and those short runways off a non-precision approach, stick with it. If not, you'll have to come up with another solution.

I'm pretty sure I can, under normal circumstances. I won't try to land on a 2500 foot runway with no flaps or only 10*, but 400 feet is plenty of height to dump 20-30* from, provided I'm not over the runway before I see it and/or I'm above circling MDA (and can do a CTL visually).

Frankly, I think you should give up on your instructor, but that's a decision for you to make.

I've thought about it, but that would mean training outside the club. It's a last resort solution for me.

Not all approaches are ILS, and not all end up at 5000+ runways.
If so, you're not ready for the IR practical test, because that's something you have to be able to do to be sure of passing it.
I know plenty of approaches in your neck of the woods ending at much shorter runways than that.

Oops, that's not what I meant. If you add that the runway is slick I'm not going out in that weather anyway. If it's low weather, in real life I think I would probably apply higher minimums than the legal MDA. I don't know of any straight-in approaches to 2600 ft runways around here, but if I was going to try going into one in really marginal weather (big if), I think I would probably hold myself to at least circling minimums.

My CFII won't take off from VLL if the ceiling is less than 1000 feet though even the circling MDA for the RNAV 9 is 700 AGL. Would the DPE have failed him on his IR checkride if s/he'd known that?

 

[bbchien]

My CFII won't take off from VLL if the ceiling is less than 1000 feet though even the circling MDA for the RNAV 9 is 700 AGL. Would the DPE have failed him on his IR checkride if s/he'd known that?

DH is 531 and he wants 1000? You're gonna be down at 531 agl for TWO MILES and once in a straight in position to land, you can safely descent to whatever looks normal to you and you'll have 90 seconds to get the airspeed down.

You're givin me some doubts about this fellow. The critical items here are tailwind and visibility. Ceiling has LITTLE to do with it.

As you get slowed down to 65 knots, you could land with a 10 knot tail wind straight in and still get stopped nicely. Look at the C172 POH!

CTL? that's a last resort.

 

[azure]

Bruce, I can't believe you're dissing a pilot for having conservative personal minimums. I'm sure that if visibility wasn't an issue and the wx was really as reported he could get down, but actual ceilings can be worse than reported. AWOSs are often inaccurate, and ceilings can come down fast.

CTL... is my fallback in case I can't spot the field in time. That happens to me a lot! The last time I went to 3DA the reported vis was 7 but I was literally over the field before I saw it. Try 76G sometime at night... I know, there's no instrument approach but coming back from the NW, another pilot and I once passed right over the field and were crossing back over from the other direction before either of us saw it. The beacon is blocked toward the NW and the runway lights are hard to spot.

Thanks for the discussion everyone.

 

[bbchien]

I'm not dissing his minimums, Liz, but I would have expected a CFI-I to have had a discussion about landing downwind vs. CTL safety, and where on the Final approach your VDP is, and what the wrinkle is that causes him/her to stay with 1,000. And exampl might be, the runway runs dowhill to the East. That might mean something.

In the case of the RNAV to 09, you have a 4.9 mile final at 531. If you have 5 mile visibility under 600 ceilings, you have an easy downwind landing so long as you don't have more than a 10 knot TW. The 172N table that I have doesn't give numbers for more than a 10 knot TW.

Now looking at Jepp, it DOES go donward 98 feet (799 to 701). But this should be discussed and would be a reason why you NEED to CTL. Discussion, Discussion!!! He should be telling you WHY.

The single most dangerous Instrument maneuver is CTL, and I point out the situation that if you get the airport under the ceiling form 4-3-or 2 miles out you have PLENTY of real world time to get it slowed down. With 100 feet over 3500 that's 2.8% and there is NO performance table for that. THAT would be a reason for requiring a CERTAIN CTL for mins. (west winds).

The downwind landing is often the preferred maneuver and is the safety pick. But he has to discuss this with you so that you 'get it".

I did not mean it come on so strong but the WHY is mondo important in the teaching.... (and did you really mean 76G? According to Jepp, it has no approaches. Ariports with approaches have tougher lighting standards. Finding a VFR only airport at night is a different ball of wax!)

 

[DutchessFlier]

Originally Posted by Wiki
The 1979 model "N" increased the flap extension speed for the first 10 degrees to 115 knots (213 km/h). Larger wing tanks increased the optional fuel to 66 US gallons (250 l).[5]

Ahem....I am sorry, but I own a 1979 172N: POH Flap Extension: 10* below 110 and long range tanks: 54 gals / 50 gals usable>

I dunno where the poster got 10* and 115 kts or 66 gal fuel

 

[ScottM]

Originally Posted by Wiki
The 1979 model "N" increased the flap extension speed for the first 10 degrees to 115 knots (213 km/h). Larger wing tanks increased the optional fuel to 66 US gallons (250 l).[5]

Ahem....I am sorry, but I own a 1979 172N: POH Flap Extension: 10* below 110 and long range tanks: 54 gals / 50 gals usable>

I dunno where the poster got 10* and 115 kts or 66 gal fuel

From the reference cited and that you quoted. See the number 5? It links to this book

http://www.worldcat.org/search?qt=worldcat_org_all&q=0830609121

 

[bbchien]

We've talked about the VDP. According to him the VDP on that particular approach is where the final segment intersects the normal visual glidepath, assuming the runway environment is in sight. If it's marked with a bold "v" on the plate then that's the outermost point you can descend below MDA from. Is that wrong?

That is correct in a transport category aircraft in which there is only one airspeed at which you will approach and land, Vref. It can be true in a Baron if it's one placarded against slip. But there are many types, the C172 among them (which tolerates a wide variety of landing speeds), in which if you need to get down, you certainly can. You CAN be conservative and just go missed....but one day you will need to get in, and it's good to know that you can, and not have if "foreign" to you. Ice accreted on approach would be one such situation. Do you really wnat to climb back up into it? Remember you're a Michigan-er.

I'll ask him why 1000, in more detail, next lesson. He didn't give a detailed reason beyond what I already said. It might be partly the downslope but it might not be. He didn't specifically say anything about CTL in this context.

I'll ask him more about CTL next time too. I know it's easy to lose the field that way and end up back in the goo or worse, but I don't feel up to cutting power and landing from a 1/2 mile final at 500 feet. If there's a tailwind to boot?

How about a mile and a half final from 500 feet- which is what you might have under a 700 foot sky with 2 mile vis. That's actually leisurely.

If CTL is unsafe, I think I would just go missed.

CTL is my last choice for anything. One winter I took the Exec. Director of Lifeline, the founding board member, to Chicago via CMI where we did the downwind ILS 32R rather than the upwind LOC 14L just to have the added margin of ceiling, though the LOC was likely just makeable. We knew there would be Ice in the clouds below 4,000 and I did not want to have to deal with a miss climbing back into the clouds (despite the fack of working known ice gear).

It's all cases. Start picking his brain.

You pick your trade- runway length (8000 feet helps) vs. assurity of making it, vs climbing back into ice, it's all cases. Pump the guy's brain. If he's worth his salt, you'll be far ahead at hour 40 than from a PTS scripting CFI.

I would have aborted this delivery trip if the runway was less than 6000 feet. My ERAU mentee (who got an IPC signoff on this trip) remembers this trip well- she learned an expanded ADM on this flight. She's been a NetJets captain for several years and is sort of a godparent to my now 20-ish year old kids.

 

[taters]

Bruce, I can't believe you're dissing a pilot for having conservative personal minimums. I'm sure that if visibility wasn't an issue and the wx was really as reported he could get down, but actual ceilings can be worse than reported. AWOSs are often inaccurate, and ceilings can come down fast.

CTL... is my fallback in case I can't spot the field in time. That happens to me a lot! The last time I went to 3DA the reported vis was 7 but I was literally over the field before I saw it. Try 76G sometime at night... I know, there's no instrument approach but coming back from the NW, another pilot and I once passed right over the field and were crossing back over from the other direction before either of us saw it. The beacon is blocked toward the NW and the runway lights are hard to spot.

Thanks for the discussion everyone.

Liz.
I dont think Bruce was slamming personal minimums...I think he was pointing out a important distinction between vis and ceiling...vis is much more a controlling factor than ceiling IMO..but you are correct about AWOS being wrong sometimes...with that said you could easily "average" the closest wx reports to make an appropriate conjecture as to the accuracy of the AWOS....Again not slamming personal minimums...but 900 ft and 10 miles is a heck of alot different than 900 ft an 1 1/2 half mile vis..I personally find RW and APT lights easier to find at night in IFR (especially for CTL)...but thats me..
Good luck ,have fun ,and be safe!

 

[DutchessFlier]

From the reference cited and that you quoted. See the number 5? It links to this book

http://www.worldcat.org/search?qt=wo...l&q=0830609121

Thx for the feedback and reference...but that author should be referred to the POH..his information is incorrect.

 

[ScottM]

From the reference cited and that you quoted. See the number 5? It links to this book

http://www.worldcat.org/search?qt=wo...l&q=0830609121

Thx for the feedback and reference...but that author should be referred to the POH..his information is incorrect.

Can you quote and source something that would show that?

I mean right now what we have is a source from an published author with over 10 books on aviation. Then there is a Internet posting that says he is wrong without any support. See what I mean? I am not saying either opinion is right or wrong but one is certainly, at this time, sounding more credible than the other. Considering that in new models of 172s the 10% flap speed is above the white arc (100 or 110 knots) it is plausible that a C172N would have also been capable of this given some certification data and other administrative hoops fro, the FAA for Cessna to jump through. That would have then been published in a change notice or new manuals.

 

[Trapper John]

Can you quote and source something that would show that?

I mean right now what we have is a source from an published author with over 10 books on aviation. Then there is a Internet posting that says he is wrong without any support. See what I mean? I am not saying either opinion is right or wrong but one is certainly, at this time, sounding more credible than the other. Considering that in new models of 172s the 10% flap speed is above the white arc (100 or 110 knots) it is plausible that a C172N would have also been capable of this given some certification data and other administrative hoops fro, the FAA for Cessna to jump through. That would have then been published in a change notice or new manuals.

I believe if Cessna made a change to permit some or all 172Ns to have a greater flap extension speed, that would have to be reflected in a revision to the Type Certificate.

I don't see that in Revision 79 of the Type Certificate here, but maybe there is something else out there?

http://www.airweb.faa.gov/Regulator...4e90061c5bf3b1862576260063e599/$FILE/3A12.pdf


Trapper John

 

[azure]

I believe if Cessna made a change to permit some or all 172Ns to have a greater flap extension speed, that would have to be reflected in a revision to the Type Certificate.

I don't see that in Revision 79 of the Type Certificate here, but maybe there is something else out there?

http://www.airweb.faa.gov/Regulator...4e90061c5bf3b1862576260063e599/$FILE/3A12.pdf


Trapper John

Where in that document is there mention of the greater 10 degree flap extension speed for any 172, even the later models? Maybe I am missing it, but I don't see it anywhere in there.

Also, I notice that earlier models had a Vfe of 87 knots but then in the middle of the 172M run, they reduced Vfe by 2 knots to 85. That applies to all later models too as far as I can tell.

(I just checked my club's 172M's SN and it would have Vfe = 85, not 87 as I had thought.)

 

[Clark1961]

The discussion on flap extension speed is sort of interesting. When working on my PP, the pre-solo test required the student to know that the flap extension speed for the 172N was 110 knots for the first 10 degrees. We flew all the 172s that way. None of the white arcs started at 110, that's fer sure! Also, none of the "don't slip with flaps" hysterical instructors batted an eye at extending the flaps the first 10 degrees above 85.

 

[gismo]

Where in that document is there mention of the greater 10 degree flap extension speed for any 172, even the later models? Maybe I am missing it, but I don't see it anywhere in there.

Also, I notice that earlier models had a Vfe of 87 knots but then in the middle of the 172M run, they reduced Vfe by 2 knots to 85. That applies to all later models too as far as I can tell.

(I just checked my club's 172M's SN and it would have Vfe = 85, not 87 as I had thought.)

I suspect that the 87 vs 85 Kt is related to an IAS/CAS issue. I also searched the entire TCDS and found nothing related to 10° flap usage above Vfe.

 

[gismo]

The discussion on flap extension speed is sort of interesting. When working on my PP, the pre-solo test required the student to know that the flap extension speed for the 172N was 110 knots for the first 10 degrees. We flew all the 172s that way. None of the white arcs started at 110, that's fer sure! Also, none of the "don't slip with flaps" hysterical instructors batted an eye at extending the flaps the first 10 degrees above 85.

On the 172s with a electric flaps and a flap "pre-select" (vs the toggle switch) there was an indication of the appropriate Vfe for each detent and IIRC they were color coded with white and blue. I believe that the ability to use partial flaps came into being concurrently with the change to the pre-select flap control. Furthermore it's my understanding that no structural changes were made to the flaps or flap actuator at that time, therefore it should be safe/harmless albeit "illegal" to use up to 10° flap at the higher IAS (as perscribed on the later model 172s).

 

[azure]

About the 85 vs 87 KCAS being IAS/CAS related: could be. Note 4 is about the calibration tables.

On the 172s with a electric flaps and a flap "pre-select" (vs the toggle switch) there was an indication of the appropriate Vfe for each detent and IIRC they were color coded with white and blue. I believe that the ability to use partial flaps came into being concurrently with the change to the pre-select flap control.

Hmmm, I no longer fly the '78 172N but it had the pre-select flaps and the POH doesn't mention the partial flaps above Vfe. I don't decall the detents being color-coded, but they were badly worn. I believe the ones in the '80 172P are color coded.

Furthermore it's my understanding that no structural changes were made to the flaps or flap actuator at that time, therefore it should be safe/harmless albeit "illegal" to use up to 10° flap at the higher IAS (as perscribed on the later model 172s).

Lance, if this is correct then my OP is moot and my "problem" is a non-issue. So where could one look for an authoritative answer to this??

 

[poadeleted20]

My CFII won't take off from VLL if the ceiling is less than 1000 feet though even the circling MDA for the RNAV 9 is 700 AGL.

Depart with a sub-1000-foot ceiling? In a heartbeat, as long as I don't have to count on getting back in. With a 300-1 takeoff min even for the commercial operators, it wouldn't bother me in the least, especially with all the other good takeoff alternate airports in the area if I have to get back down in a hurry for some reason. I might, however, be hesitant to launch on a training flight with the weather forecast less than 300 above the lowest mins since I don't want to end up stuck somewhere else.

Would the DPE have failed him on his IR checkride if s/he'd known that?

Of course not. But if he flew that RNAV 9 approach with the winds favoring 9 and was unable to land safely straight in on 9 after spotting the runway about a mile and a half out (max TERPS descent gradient), the DPE probably would fail him. Think about it: 600 feet above touchdown, 100 knots, clean, 9000 feet from a 3500-foot runway -- can you do that comfortably every time? If not, you need more work or a better system, because landing the plane out of the approach is a pass/fail item in the PTS, and that's why I teach my IR trainees to arrive at the "commit to land" point in a configuration which allows a safe landing on even the shortest instrument runways.

 

[poadeleted20]

Lance, if this is correct then my OP is moot and my "problem" is a non-issue. So where could one look for an authoritative answer to this??

The AFM "Limitations" section.

 

[azure]

I might, however, be hesitant to launch on a training flight with the weather forecast less than 300 above the lowest mins since I don't want to end up stuck somewhere else.

Exactly, I have no reason to think there was more to it than that.

Think about it: 600 feet above touchdown, 100 knots, clean, 9000 feet from a 3500-foot runway -- can you do that comfortably every time?

600 feet up and a mile and a half out? In all honesty: normally i.e. winds calm or favoring the runway yes, easily. With a 5 kt tailwind I'd be uncomfortable, and with a 10 kt tailwind I'd land opposite direction or go somewhere else. I'm not ready for the checkride yet though, I know this.

 

[Pilawt]

Hmmm, I no longer fly the '78 172N but it had the pre-select flaps and the POH doesn't mention the partial flaps above Vfe. I don't decall the detents being color-coded, but they were badly worn. I believe the ones in the '80 172P are color coded.

The "graduated" Vfe (110 KIAS for the first ten degrees of flap) was introduced on the C-172N for the 1979 year model, s/n 17271035 and up.

 

[poadeleted20]

600 feet up and a mile and a half out? In all honesty: normally i.e. winds calm or favoring the runway yes, easily. With a 5 kt tailwind I'd be uncomfortable, and with a 10 kt tailwind I'd land opposite direction

That's why we teach CTL's as well as straight-ins, but in terms of getting slowed and configured, CTL's are easier because you have more distance to fly after spotting the runway in a low-vis situation. Of course, there are a lot of other issues with CTL's, but getting slowed and configured isn't one of them.

 

[azure]

The AFM "Limitations" section.

Of course, that's "legally" authoritative. But what is the real scoop from a safety/mechanical POV?

Interestingly the POH nowhere says explicitly that partial flaps are prohibited above 85 KIAS. It says do not exceed 85 KIAS with "flaps down" and it calls the white arc the "full flaps operating range".

Is 10* considered "down"?

No I will NOT be a test pilot for this. And it's moot if the DPE considers it prohibited. But I'd like to know if it really is.

 

[ScottM]

The discussion on flap extension speed is sort of interesting. When working on my PP, the pre-solo test required the student to know that the flap extension speed for the 172N was 110 knots for the first 10 degrees. We flew all the 172s that way. None of the white arcs started at 110, that's fer sure! Also, none of the "don't slip with flaps" hysterical instructors batted an eye at extending the flaps the first 10 degrees above 85.

When I was doing my primary training for my PP LICENSE (that was for Ed) I was flying a 172R or a 172S and one night while reading the POH I came across the statement saying that 10% of flaps could be used at 110knots and that rest of the flaps had to be at Vfe or less.

The next time I flew I started to put flaps down at 100knots and the CFI about poped a gasket. He was afraid the flaps were about to come off and gave me a big lecture about the white arc. As I was landing I had more things on my mind, but once we landed I pulled out the AFM and showed him the appropriate section. His jaw hit the ground as he had never known that. He thanked me and said that being able to use flaps like that would help him with a couple of students that were having some trouble with approaches.

To Liz, check your AFM, that is where it is legal or not. The statement about the 172N may be true but it would need to pulled into your AFM. One might want to try contacting the FSDO if we cannot find a definitive answer here on PoA.

 

[TMetzinger]

One might want to try contacting the FSDO if we cannot find a definitive answer here on PoA.

It's a shame that there's more likely a uniform consensus on regs here on POA than there is at the various FSDOs.

 

[poadeleted20]

Of course, that's "legally" authoritative. But what is the real scoop from a safety/mechanical POV?

Good question, and I don't know the answer. Note, however, violating a book limitation is an automatic failure on all practical tests.

Interestingly the POH nowhere says explicitly that partial flaps are prohibited above 85 KIAS. It says do not exceed 85 KIAS with "flaps down" and it calls the white arc the "full flaps operating range".

Is 10* considered "down"?

The C-172 TCDS uses the word "extended," not "down," as part of that limitation, and even one degree is "extended." Let us say that absent relief from that limitation such as "extension up to 10 degrees is permitted below 110 KIAS," any extension however slight is sufficient to complete the offense.

 

[azure]

To Liz, check your AFM, that is where it is legal or not. The statement about the 172N may be true but it would need to pulled into your AFM. One might want to try contacting the FSDO if we cannot find a definitive answer here on PoA.

The AFM doesn't say anything beyond what is in the POH, and the POH uses ambiguous language, i.e. flaps "down" vs "up". It does define Vfe as "maximum flap extended speed" but then calls the white arc the "full flap operating range" and says the upper limit is the "maximum speed with flaps extended", which might be taken to mean that "extended" is the same thing as "full flap".

The TCDS (see post #137) doesn't seem to say anything about the partial flaps above Vfe for any model of C-172.

So does the fact that it's in the later model POH's reflect a real design change, or just that they finally had data for more than the two configurations down and up when those manuals were published?

 

[azure]

Good question, and I don't know the answer. Note, however, violating a book limitation is an automatic failure on all practical tests.

I figured it would be. Drat. It's still something that would be good to know, IMO.

 

[gismo]

The AFM "Limitations" section.

Assuming the airplane in question has an approved AFM. One thing that puzzles me is that since the TCDS for all the 172s we've been talking about clearly statest that Vfe is 85/87 Kt without regard to the amount of flaps deployed, the AFM that indicates 110 Kt is OK with ten or less degrees of flaps is in conflict with the TCDS. I thought that the TCDS superseded the AFM when there is a discrepancy. Have I got that backwards?

 

[gismo]

Of course, that's "legally" authoritative. But what is the real scoop from a safety/mechanical POV?

Interestingly the POH nowhere says explicitly that partial flaps are prohibited above 85 KIAS. It says do not exceed 85 KIAS with "flaps down" and it calls the white arc the "full flaps operating range".

Is 10* considered "down"?

No I will NOT be a test pilot for this. And it's moot if the DPE considers it prohibited. But I'd like to know if it really is.

Liz, Cessna would be the only practical place to find out whether there was a structural change made to allow 10° flaps to be used below 100 Kt. But even if (as I suspect) this is not the case, you still wouldn't be legal to do so in a plane that isn't so placarded and/or doesn't have an exception to Vfe in the model specific AFM. In any case I personally wouldn't be too concerned about damage using 10° flaps at 100 kt (or was it 110 kt), but I wouldn't plan to do so on a checkride either.

 

[poadeleted20]

Assuming the airplane in question has an approved AFM.

If it was built since 1977, it does.

One thing that puzzles me is that since the TCDS for all the 172s we've been talking about clearly statest that Vfe is 85/87 Kt without regard to the amount of flaps deployed, the AFM that indicates 110 Kt is OK with ten or less degrees of flaps is in conflict with the TCDS.

The TCDS may not include all the limitations. The AFM does.

I thought that the TCDS superseded the AFM when there is a discrepancy. Have I got that backwards?

I didn't know that was true. However, in this case, I'll go with the AFM and the marking on the flap indicator, and not even think twice about it.

 

[azure]

Liz, Cessna would be the only practical place to find out whether there was a structural change made to allow 10° flaps to be used below 100 Kt. But even if (as I suspect) this is not the case, you still wouldn't be legal to do so in a plane that isn't so placarded and/or doesn't have an exception to Vfe in the model specific AFM. In any case I personally wouldn't be too concerned about damage using 10° flaps at 100 kt (or was it 110 kt), but I wouldn't plan to do so on a checkride either.

I know it wouldn't be legal, and would be an automatic fail on a checkride, but still, if I was in a bind on a real flight and needed to get configured fast, it would be good to know that I could start to do it from ~100 kts and not worry about damage.

 

[DutchessFlier]

I spoke to Cessna yesterday. The technician told me plainly that the 10* and 110 kts is a AFM limitation to remain within the structural envelope for flap extension. The Certificated flap extensions only apply to those greater than 10* (ie the range of 20* to 30* or 40* flaps extension depending on the model year and SN) and the white arc limitation of 85kts. So....110 and 10* is an AFM/POH operating limitation but NOT a type certificate issue...20* or greater and 85kts IS a type certificate limitation. Interesting note is the change in total flap travel from 40* to 30* I believe after the 1979 models...although I have 40* in 71D, I rarely use it (unless I have to drop her in for a very short field) and have been told that some owners have placed a stop in the flap switch to prevent the flaps from full travel to 40* (not sure if that's a legal modification) I asked the tech about flap travel and he said that there was no structural design change to the plane when that change from 40* to 30* was made just a change to how far the flap travel was allowed to go mechanically and the switch was redesigned to allow max travel of 30*.

 

[poadeleted20]

I spoke to Cessna yesterday. The technician told me plainly that the 10* and 110 kts is a AFM limitation to remain within the structural envelope for flap extension. The Certificated flap extensions only apply to those greater than 10* (ie the range of 20* to 30* or 40* flaps extension depending on the model year and SN) and the white arc limitation of 85kts. So....110 and 10* is an AFM/POH operating limitation but NOT a type certificate issue...20* or greater and 85kts IS a type certificate limitation.

Either way, don't extend the flaps at all above 85 KIAS in a 172 that doesn't have the 10/110 approval in the AFM/POH.

Interesting note is the change in total flap travel from 40* to 30* I believe after the 1979 models...

This was done to allow a gross weight increase from 2300 to 2400 lb. The limiting factor had been the balked landing climb gradient with full flaps. By reducing flap travel 10 degrees, they were able to make the climb gradient while 100 lb heavier.

although I have 40* in 71D, I rarely use it (unless I have to drop her in for a very short field) and have been told that some owners have placed a stop in the flap switch to prevent the flaps from full travel to 40* (not sure if that's a legal modification)...
I asked the tech about flap travel and he said that there was no structural design change to the plane when that change from 40* to 30* was made just a change to how far the flap travel was allowed to go mechanically and the switch was redesigned to allow max travel of 30*.

There's an STC which replaces the 40-degree flap switch with the newer one with the 30-degree limit and gives a GW increase to 2400 lb, so the modification is probably legal (but you'd have to check the aircraft paperwork to be sure).

 

[dmccormack]

I know it wouldn't be legal, and would be an automatic fail on a checkride, but still, if I was in a bind on a real flight and needed to get configured fast, it would be good to know that I could start to do it from ~100 kts and not worry about damage.

Any strut, fixed gear Cessna is draggy enough that a throttle pull back and nose lift will slow the airplane appreciably in moments.