Cowl Flaps Question

[Murdoughnut]

Still new to HP flying (Bonanza A36). Question - a guy I flew with recently opened the cowl flaps on final approach as a part of the landing checklist. His reasoning was to have them open during a go around, and so he didn't forget to open them once off the runway.

Any reason to avoid opening them on final? Too much cooling/drag?

 

[derg]

Still new to HP flying (Bonanza A36). Question - a guy I flew with recently opened the cowl flaps on final approach as a part of the landing checklist. His reasoning was to have them open during a go around, and so he didn't forget to open them once off the runway.

Any reason to avoid opening them on final? Too much cooling/drag?

Paging former Beech owner @Richman. Richman line one...

 

[Roger Roger]

When I flew an airplane with cowl flaps I always opened them after landing but it probably doesn’t matter.

 

[killbilly]

Still new to HP flying (Bonanza A36). Question - a guy I flew with recently opened the cowl flaps on final approach as a part of the landing checklist. His reasoning was to have them open during a go around, and so he didn't forget to open them once off the runway.

Any reason to avoid opening them on final? Too much cooling/drag?

One of my crew mates owns an A36 and says he opens after landing but that it really wouldn't matter a whole lot either way.

 

[Murdoughnut]

One of my crew mates owns an A36 and says he opens after landing but that it really wouldn't matter a whole lot either way.

Thanks - that's helpful. I think I'll keep on doing it.

I'm a bit frustrated with myself at the moment because I damn near took off with full flaps yesterday. Fortunately my safety pilot caught it while I was advancing power. They changed our checklist and moved flap retraction to the during taxi checklist. I was tunnel vision focused on taxiing between hangars (was taking the plane out of maintenance) and went more quickly through it than normal to keep my head up, and apparently missed it altogether.

Learning lesson for sure, and my SP and I went back through the checklist once we got into cruise to see how I missed it, but felt like an idiot.

 

[ppragman]

When I flew an airplane with cowl flaps I always opened them after landing but it probably doesn’t matter.

Me too. Part of the after landing flow, and in the interior in the winter often we only opened them half way after landing as the CHTs would plummet if you did… which is kind of wild.

 

[Roger Roger]

Thanks - that's helpful. I think I'll keep on doing it.

I'm a bit frustrated with myself at the moment because I damn near took off with full flaps yesterday. Fortunately my safety pilot caught it while I was advancing power. They changed our checklist and moved flap retraction to the during taxi checklist. I was tunnel vision focused on taxiing between hangars (was taking the plane out of maintenance) and went more quickly through it than normal to keep my head up, and apparently missed it altogether.

Learning lesson for sure, and my SP and I went back through the checklist once we got into cruise to see how I missed it, but felt like an idiot.

Our company has a 5 item memory list we do before lineup that’s only things that will literally kill you. It might be worth coming up with your own. Something like Fuel Flaps Trim (I think those are the only real killer items on a Bo). The key is it has to be short and only killer items. I even think GUMPS has too many non-essential items-you won’t crash if you land with the mixture lean or the prop pulled back.

 

[Murdoughnut]

Our company has a 5 item memory list we do before lineup that’s only things that will literally kill you. It might be worth coming up with your own. Something like Fuel Flaps Trim (I think those are the only real killer items on a Bo). The key is it has to be short and only killer items. I even think GUMPS has too many non-essential items-you won’t crash if you land with the mixture lean or the prop pulled back.

My SP mentioned that his "lights, camera, action" list includes him checking flaps. I use the same words every time, but never incorporated flaps into it - but I will now. Everything I need to check under "action" is more or less in the same place on the lower middle panel.

 

[Roger Roger]

My SP mentioned that his "lights, camera, action" list includes him checking flaps. I use the same words every time, but never incorporated flaps into it - but I will now. Everything I need to check under "action" is more or less in the same place on the lower middle panel.

See, I don’t even like the lights camera action because again, none of that will kill you.

 

[ppragman]

See, I don’t even like the lights camera action because again, none of that will kill you.

Yes - that was my philosophy as well more or less, have a list of items that will kill you or embarrass you and religiously do that prior to every take off in that airplane.

That way when it’s your gazillionth leg of the day and you read the checklist but don’t actually comprehend any of it you still have a final check of stuff that will save you from yourself.

In the Navajo and the king air it was:

CIGARTAB

controls
instruments
Gas
Avionics
Radios
Trims
Annunciators
Bleeds and Brief

Navajo didn’t have bleed air, but I used that to remember the heater.

The briefing for the reminder to pause and think about what I’m doing before I do it.

The PC12 was GLIPFY-B if memory serves.

Gas
Lights
Ice Protection
Pusher
Flaps
YAw Damp
Brief (for the same reason as above)

But a lot of it really doesn’t matter, IMO it’s about double checking yourself and building habits that catch mistakes that will kill or embarrass you.

 

[ppragman]

There was a brief period of time where I was flying 2 vastly different Navajos, a pilatus and a caravan and would routinely fly all 3 types in a day. Checking the landing gear like a putz religiously in the van probably helped me not gear up the Navajo - which one of our pilots eventually did. The key is make sure your habits are strong enough to save you from yourself.

 

[Roger Roger]

Yes - that was my philosophy as well more or less, have a list of items that will kill you or embarrass you and religiously do that prior to every take off in that airplane.

That way when it’s your gazillionth leg of the day and you read the checklist but don’t actually comprehend any of it you still have a final check of stuff that will save you from yourself.

In the Navajo and the king air it was:

CIGARTAB

controls
instruments
Gas
Avionics
Radios
Trims
Annunciators
Bleeds and Brief

Navajo didn’t have bleed air, but I used that to remember the heater.

The briefing for the reminder to pause and think about what I’m doing before I do it.

The PC12 was GLIPFY-B if memory serves.

Gas
Lights
Ice Protection
Pusher
Flaps
YAw Damp
Brief (for the same reason as above)

But a lot of it really doesn’t matter, IMO it’s about double checking yourself and building habits that catch mistakes that will kill or embarrass you.

See, IMHO those are too long. In the PC-12 the company callout is FASTR but several of those are jeeeeetttt things so it would get shortened to Flaps Air mode (only because the plane yells at you if you don’t do it) Trim Runway alignment. In the jeeeeetttt it’s Flaps Airspeeds (and I don’t even like this one, if you don’t have your speeds posted you won’t die) Spoilers Trim Runway alignment. People like to start adding a bunch of other • under various letters and I don’t like it.

 

[ppragman]

See, IMHO those are too long. In the PC-12 the company callout is FASTR but several of those are jeeeeetttt things so it would get shortened to Flaps Air mode (only because the plane yells at you if you don’t do it) Trim Runway alignment. In the jeeeeetttt it’s Flaps Airspeeds (and I don’t even like this one, if you don’t have your speeds posted you won’t die) Spoilers Trim Runway alignment.

Probably - I just found something that worked for me and was quick. You could probably get it down to 2 or 3 things and go with it.

I shortened CIGARTAB from something I read that was similar that was like CIGTERFLIPPS or something ridiculously long and complex, but you’re right it could be shortened. Still cut worked for me and I caught a lot of errors that I might have missed while tired.

I think that the key is to build it off of your own mistakes.

 

[bimmerphile]

my lancair pretakeoff
Latches (canopy)
fuel (mixture and boost pump)
flaps
trim

as those are the big ones that will make a takeoff very spicy if missed. just make one up that becomes a natural flow so it ends up second nature, mine starts at the canopy and goes across the panel and back to the stick

 

[killbilly]

my lancair pretakeoff
Latches (canopy)
fuel (mixture and boost pump)
flaps
trim

as those are the big ones that will make a takeoff very spicy if missed. just make one up that becomes a natural flow so it ends up second nature, mine starts at the canopy and goes across the panel and back to the stick

In the RV it's..."engine....running....go".

I'm kidding. I use a standard "lights, camera (transponder in the FRZ is *really* important) action" - the RV will take off and fly happily with full flaps. It ain't efficient but it'll do it.

 

[bimmerphile]

to the OP original question
depends on the weather and how long the approach is, if chts are already pretty cool and youre not dragging it in id wait to open after landing
cowl flaps is not a big deal to open on a go around, and I’d think most GA airplanes wouldnt smoke a cylinder in the 15 sec you make a go around. power gear flaps trim cowl flaps

leaving the gear down by accident on a go around will probably elevate CHTs more than leaving cowl flaps closed

 

[Richman]

Soooo, my take....

I don't think shock cooling is really that big a thing...I mean, what happens when you fly through rain? Talk about quenching. I'm all for not tormenting your engine unnecessarily, but this was one of those things I wasn't particularly religious about. I'm sure more than one person has packed it in by doing an unreasonable amount of fussing with the engine trying to keep it warm and not really paying attention to the flight path.

Ok, that said, on the flip side, you can really smoke a big bore Conti fairly easily, so the real focus should be on the mixture. As long as you got to the cowl flaps eventually, you aren't going to do any "ooops...<bang>" damage. Trying to go around, getting back into the pattern or busy joining the missed approach while you're at a lean mixture while WOT? Yea, that will be far, far worse than leaving the cowl flaps closed for a little bit.

My personal technique was to open them entering the pattern, or once my primary descent to IFR vectoring altitude was done, for the reasons stated above. You're going to be slowing up, and may be operating at more than idle, especially if vectors are extensive or the pattern is widebody style. Open them when the workload is low, so you aren't missing them when it is high.

CHT is key to cylinder longevity. The key to managing the CHT is know what your EGT/TIT should be and how to manage it. The yield curve isn't linear, and once you get above 420, you start eating into cylinder life. I personally set my JPI to alarm at 390. It wasn't "OMG 390!!!! master warning!", but a reminder to take steps to stop the increase. Crack open the cowl flaps, lower the nose, richen/lean the mixture depending on which side of peak you were on, etc.

I had a 550 with the TAT turbo in my V35. It was PACKED in there. I ran it LOP, but ran it by the TAT book and had the fuel controller dialed in. My CHTs never got above the low 300s in the climb and the TIT was in the low 1200s (well, ya, burning 35 GPH, you were practically drowning it). Once in cruise, running at WOT/2500 with 17.5 GPH, that was about 80d LOP, and my TIT was around 1440-1500. CHTs were in the mid 300s, and I had one outlier that would float around 380 if the weather was really hot. For descents, I'd pull it back to 18-21" and stick the nose over, and I got what I got. Bottom of the descent, level off, power up to 25", open the cowl flaps, and you were done fussing. The big, big, big takeaway with the TAT was you absolutely HAD to get the mixture rich for a go-around, otherwise the temps would get hot in an instant.

FWIW, you need someone who knows WTF they're doing if you're tinkering with the fuel controller. They need to follow the Continental SB TO. THE. LETTER.

 

[MidlifeFlyer]

Still new to HP flying (Bonanza A36). Question - a guy I flew with recently opened the cowl flaps on final approach as a part of the landing checklist. His reasoning was to have them open during a go around, and so he didn't forget to open them once off the runway.

Any reason to avoid opening them on final? Too much cooling/drag?

opening cowl flaps on final in case of a go-around has been my SOP for years in various airplanes. By the time you are on final, you have reduced power sequentially a number of times. Check your CHT. Over-cooling should no longer be an issue.

 

[Fixtur]

At my shop (Senecas and Navajos) cowl flaps stay closed. On the go-around Mixtures->props->throttle keeps temps well within range up to the missed approach altitude.

Cowl flaps are opened as an after-landing item.

 

[form810]

Still new to HP flying (Bonanza A36). Question - a guy I flew with recently opened the cowl flaps on final approach as a part of the landing checklist. His reasoning was to have them open during a go around, and so he didn't forget to open them once off the runway.

Any reason to avoid opening them on final? Too much cooling/drag?

Closed on approach. Open on Go-Around. Because: Amplitude of Heat.

If it's too hard to understand this and recall it at appropriate moments during the flight regime... Well then, I guess just avoid aviation and go back to whatever you do when you're not bungling up an aircraft and putting people or equipment at risk.

There's a checklist for both Approach/Landing and Go-Around. Like the two departures at SFO, BOTH of these checklists should be briefed BEFORE commencing the approach.