Getting low and slow on short short final

[dtuuri]

I tend to discount personal opinions from those who sound a bit off the beaten track. However, again, I respect your right to your own opinion.

I shouldn't sound "off the beaten track" to anybody referencing the POH. No mention of blue line nor 89 KIAS (blue line) therein:
pa34-200t-seneca-ii-poh.pdf (racecityfo.com) as it pertains to landing approaches. Beware of following beaten tracks through the weeds — poisonous snakes abound.

 

[Tantalum]

HUH. You are saying you have a power setting of say 2300 RPM. You reduce the throttle until the props drop to 2100 RPM and if you push the props levers forward the RPM increases? That cannot happen unless something is really screwed up.

Talking RPM and MP I've got the blue knobs forward and MP around 15 inches

But in this example I've never been that slow in a twin (outside of short final) where if I pull throttle to idle they reduce to 2100. Depending on what I'm flying they're screaming anywhere from 2500 to 2700

But the bottom line is I was trained (initial multi training, check rides, proficiency checks, recurrent) to stay at blue line until short final / landing made. I don't know of any light GA twin that will accelerate back to blue line (single engine climb) with gear and flaps down. Sure you can put the nose down and lose gravity, but if you're low to the ground that's less than ideal. This does not mean that we're coming over the numbers and starting the flare at blue line, that'd be crazy and result in a huge float. But I'm also not sitting three miles out on the approach dilly dallying under blue line.

Vmc, red line, is a different matter, but that will just keep the plane upright and "controllable", has nothing to do with climb

Landing, on the other hand, has you well above the obstacles with a lot of excess power available from gravity just by pointing the nose down and the plane is dirtier, thus reducing the most aerodynamically clean airspeed for reference, as well as being at less weight.

Landing has us well above the obstacles?? Maybe at the FAF.. but landing has you near the ground, and getting closer.

I wouldn't say you have excess power, sure you can point the nose down, but by that logic the plane has the most power in cruise, and has an increasing amount of power as you take off and climb. During landing that regime is shrinking, money is flowing out the bank so to speak

I genuinely don't know what this means "plane is dirtier, thus reducing the most aerodynamically clean airspeed" a dirty plane has loads of drag. A clean plane twin GA will barely climb on one engine as it is. A dirty one, forget it, you are only going down. But hey you have all that excess power so why worry, right?


Anyway, we can disagree. For those who fly with me in a twin we'll be accelerating to blue line shortly after rotation and staying above it until we're a mile out or less.

 

[dtuuri]

Landing has us well above the obstacles?? Maybe at the FAF.. but landing has you near the ground, and getting closer.

In comparison to the takeoff regime blue line is designed for: takeoff climb. In comparison, during landing, you have altitude, speed and extra power available in the form of potential energy.

I genuinely don't know what this means "plane is dirtier, thus reducing the most aerodynamically clean airspeed" a dirty plane has loads of drag. A clean plane twin GA will barely climb on one engine as it is. A dirty one, forget it, you are only going down. But hey you have all that excess power so why worry, right?

Your optimum speed for least drag is influenced slower by flaps, gear and a lighter weight than you have during takeoff, so chasing blue line (a takeoff quick-reference speed) during landing is a fool's errand. A sudden windmilling engine during a power approach would require you to go below glide path to maintain blue line, for example. Zooming in at blue line, when it's way above 1.3 Vs raises the chance of landing long, unnecessary brake wear and engine wear not to mention more cabin noise and passenger concern as you increase RPMs with the prop control. I don't think professional pilots should fly this way although there may be a case for newbie multiengine students being taught like this to simplify procedures a tad.

 

[midwestpa24]

I am not clear which issues you feel that I am raising.

I have suggested to prepare for landing at glide slope intercept and to be on a stabilized approach no later than 500’ AGL.

Sorry, got you mixed up with the OP. My comment was not directed to you.

 

[midwestpa24]

I shouldn't sound "off the beaten track" to anybody referencing the POH. No mention of blue line nor 89 KIAS (blue line) therein:
pa34-200t-seneca-ii-poh.pdf (racecityfo.com) as it pertains to landing approaches. Beware of following beaten tracks through the weeds — poisonous snakes abound.

You fly your plane however you want, but more twin pilots have been killed from getting too slow than too fast. I'm not saying maintain blue line until the flare, but until landing is assured. In other words, once I've given up blue line, any type of engine failure is going to result in a landing and not a go-around. Think of it as the opposite of V1 on takeoff. Something I was taught by THE Doug Rozendaal by the way.

 

[dtuuri]

Something I was taught by THE Doug Rozendaal by the way.

Same Rosendaal who wrote this? Here? BeechTalk - BT - Full prop RPM on landing?

"I push props foward when the prop comes out of the governing range.... In a single, the low pitch stops are set pretty high and this will occur long before touchdown, unless you are carrying lots of power."
​

 

[midwestpa24]

Same Rosendaal who wrote this? Here? BeechTalk - BT - Full prop RPM on landing?

"I push props foward when the prop comes out of the governing range.... In a single, the low pitch stops are set pretty high and this will occur long before touchdown, unless you are carrying lots of power."
​

Yes, and keep reading...

"In most twins the low pitch stops are much flatter and the propeller governs until you close the throttle in the flare...."

This particular post does not cover blue line operations on approach and landing, but I've trained with Doug in several twins, and the procedure was always the same.

 

[Pinecone]

There is no harm pushing the prop(s) forward while they are still governing, but it make a nasty sound to people on the ground. So you get them not liking the noise, and then someone starts a campaign to close the airport. Which the local developers want, so they can get the land. And the local politicians, since that space generates more tax dollars as houses than as an airport.

Be a nice neighbor.

 

[dtuuri]

Think of it as the opposite of V1 on takeoff.

If you want to compare light twin flying to transport category airplane procedures, Vref (1.3 Vso) is the landing reference speed to use. In fact, I think the POH for the Seneca II stipulates a landing speed range that seems like they were based on a maximum gross weight stalling speed for clean and full flaps times 1.3.

 

[dtuuri]

Yes, and keep reading...

"In most twins the low pitch stops are much flatter and the propeller governs until you close the throttle in the flare...."

This particular post does not cover blue line operations on approach and landing, but I've trained with Doug in several twins, and the procedure was always the same.

I meant only to grab this portion:

"I push props forward when the prop comes out of the governing range...."​

The rest is a distinction without much of a difference. It backs up what I said:

"5. When you push the props forward, you should be slow enough that no change occurs in sound level or RPM or drag because the blades are on the low pitch stops already."​

 

[dtuuri]

@DaveInPA, @Mongoose Aviator and @midwestpa24 :

The "Maneuver Guide" I linked to is from the Elmendorf AFB Aero club, AK. There are some interesting comments on the bottom of page 16 about landings in general that may help blue line maniacs get over their phobias: seneca_maneuvers_guide_5.9mb.pdf (jberaeroclub.com)

Note also that for instrument approaches prop rpm is increased to just 2400 RPM on final approach, not pushed full forward, and airspeed is higher than blue line (105 KIAS) until the runway is in sight, see page 28. This is within my caveat: "YMMV, depending on the specific light twin or operating procedure for a specific job, but that's how I remember it."