Well thank you @Antonio. Will consider that. Should have known that there’s “yet another article” from the Pelican’s Perch series, that covers also this topic. 
To me it sounds like “in principle could be a problem, but in real world flat-six it shouldn’t be”.
I would add…if you only seldom do it and then only for a few seconds at a time. I would encourage you to take it as a small challenge to tune your operational procedures so you do minimal use of prop brake.
UdoR wrote:
Should have known that there’s “yet another article” from the Pelican’s Perch series, that covers also this topic.
John was one of the class act’s in aviation. He is sorely missed. It was a privilege corresponding with him over the years of avsig and later when he did his courses. I wish I could have attended one of those while he was still alive.
Antonio wrote:
I would encourage you to take it as a small challenge to tune your operational procedures so you do minimal use of prop brake.
Of course.
In fact it only happened because on the ATIS it was announced that a circling approach is to be expected, where I would have had more than enough time to reduce speed, lower gear on downwind etc. But while on the glideslope tower told me that I should land straight in. That I did not expect and thus had to slow down somehow. I was quite surprised about the braking force. I had around 1500-1600 RPM before, where it seems to glide forever, and bringing RPM gradually up to 2400 was really like stepping on the brake. So I don’t mean to fly like this often, I want to understand my options before doing any harm (or not).
Best way to slow down is to slow down to the Vlo or whatever by fairly aggressively pulling up (takes only a few secs) and then dropping the gear and Flap 1.
Reducing power is also fine if you can, but avoid shock cooling (haha that old one).
UdoR wrote:
while on the glideslope tower told me that I should land straight in
Yes, when the runway is changed your planned descent profile is messed up. If POB are tolerant or limited to crew, and especially if VMC, I have sometimes used a sideslip to help with that.
I was once given an unexpected last-minute approach shortcut on arrival to Alghero from the west (FIR change just prior to arrival and with prior FIR refusing descent) and ended up descending unpressurized, gear-down, full flaps and with sideslip from over 6000ft and with pax onboard…in retrospect I should simply have refused and flown the extended approach. It must have been a case of pilot’s hubris “I-can-do-itis” or perhaps “I can get there within 90 mins”.
Also, not our case, but bear in mind some low-wing aircraft are not tolerant of prolonged sideslip due to fuel starvation.
Ideally, you should have speed-brakes. I only flew them once on a friend’s 337 and they were surprisingly effective. One more tool if needed often, and you can incur the cost and weight penalty. Are they available for Comanches?
Antonio wrote:
Are speed-brakes available for Comanches?
Yes but installing these just won’t happen.
Peter wrote:
and then dropping the gear and Flap 1.
Which limits me for practical reasons to about 90 knots.
In fact my instructor during IR training even told me some benefits of the three-blade prop, that included in particular the increased braking action on descent. And we did use it sometimes. That’s what brought it to my attention.
For direct drive engines, shock cooling considered, allowing propeller braking will not be harmful, as long as the maximum RPM is not exceeded, The RPM changes are smooth, and any RPM limitations (yellow zones on the tach) are avoided. The propeller braking will be more effective at the most fine pitch which can be achieved without exceeding the maximum RPM. It is considered bad practice to propeller brake with geared engines. Whether it’s an operating limitation varies by engine, but it’s a general rule of good piloting. It has been explained to me by the owners of expensive geared engines that the gears alternately driving and being driven creates undesired wear. It is noteworthy that I did very specifically ask RED Engines about any limitations or cautions with respect to the prop driving the engine with the A-03 diesel, and they told me it was permitted.
I also prefer sideslipping when it is convenient. If a combination of some sideslipping and fine pitch, throttle closed does not produce the desired descent, it’s probably a descent which is poorly planned, and potentially unstable. If ATC has requested such a descent, and you’re not comfortable doing it in your expensive airplane, with your expensive engine; “Cannot comply” is a reasonable response.
I have flown Mooneys with spoiler speed brakes. I was not impressed. Indeed, their effect was little such that when one stuck up (would not retract, when I selected retract) I landed with one up and one retracted, and really did not notice much – so they obviously weren’t doing much to begin with.
G-XX request more track miles.
Lost count of the times I’ve asked for decent to give 500-750fpm and been held high.
Any greater than 750fpm will overspeed my airframe. So the only option, if I’m sure the clearance isn’t imminent is reqest more track miles, or to try and slow down to deploy some flap, or gear and flap. Feels weird at 16k though.
