How can I land a PA-44 (Seminole)?

Question

I’m trying to get my ME endorsement now, and I find I can’t land very well. My instructor told me to forget everything I know about the Cessna, and that this aircraft should be landed with power. He told me to do a really low approach (compared to the Cessna) and keep the power on until about 7-10 ft off the runway, gently round out, level off (about four fingers under the horizon) and start decreasing power, wait for the aircraft to sink, then pull the column to three fingers under the horizon, power to idle, and land.

But I’m really confused:

1. Where is my aim point? I always do it depending on my feeling, so sometimes it’s unstable. Maybe use the bottom of the compass to match the runway number?
2. What’s the rate to reduce the power? My instructor told me the best condition was you touch down at the same time your power had been idle. But I don’t know when the aircraft will touchdown, so I always reduce the power to idle before the aircraft starts sinking. Is that OK?
3. When I was doing it, I didn’t know why the control column was really hard to pull during flare, and I had trimmed the aircraft on final. Maybe use more trim on a short final?

Answer 1

I have some time in a Seminole. The issue with twins that causes most of the difficulty is the speed brake effect of two propellers when you pull the power off and they go to full fine pitch. It's like you deployed a couple of drogue chutes, and makes your speed decay very rapidly and you will find yourself sinking quickly and needing large pitch inputs to try to arrest the sink, and with the Seminole's pitch behaviour this can be challenging to master.

The Seminole is not helped by having fairly high stabilator forces in pitch in the flare, and the T tail causes changes in stabilator effectiveness and sensitivity as the surface comes down into the wing's downwash during the pitch up.

You should be trimmed for hands off flight at your final approach speed (you trim to a speed - think of the trim wheel as your hands-off cruise control speed select dial) 90kts if near GW, 80kts when light. Some pilots feed in a little bit of extra NU trim just before the flare to reduce the pitch effort, but this puts your trim speed even slower, and if you go around, you will be frantically spinning it ND and pushing on the column as you accelerate to blue line - more so than if you were trimmed at Vref.

Your aim point is 3-500 feet down the runway (in big aircraft it's 1000 ft). The numbers will do fine as a reference. Your target condition is, as you are passing down below 300 ft or so, you should be trimmed with power set so you can let go of the controls and the plane will hold speed and track the glide slope without any input from you. Then it's little nudges and small power changes to correct things. The key is trim to hands off on-speed and on-slope so that the airplane works with you, not against you. For your questions:

1. Don't rely too much on crutches like standard clearances from objects in the cockpit. Your target is to have the touchdown zone simply staying in the same spot in the windshield as you close in on it, wherever that spot is. The "two fingers this, three fingers that" varies with loading so can't be used except as a very general reference for starting out.
2. In a twin like that you carry power through the round out and the start of the flare and you settle into ground effect. For starters, just leave approach power on until you are at about 5 feet then pull it to idle as you are feeling for the runway. With experience you can work on feathering the power off from a bit higher up, getting to idle just before touchdown, but it's too much to think about early on. When you want to make small or slow power reductions, it's easier to manage it by walking the levers in little alternating increments by rotating your hand.
3. The hard pull for the flare is characteristic of the Seminole and is just something you have to get used to. As I said, you can trim to a slower speed during the round out to reduce how hard you have to pull, but if you do a go around you find yourself trimmed for, say, 65kt and as it wants to accelerate you will be pushing pretty hard on the wheel to keep the nose down to accelerate to blue line while frantically reaching for trim wheel. Then if an engine quits and you are distracted doing the drill without retrimming, while holding a hard forward push, you will inevitably let it relax, and things go south.

The biggest factor that will help with your flying is mastering the use of trim for managing speed (it gets more complicated later because you pitch to speed when flying visually, but later when doing instrument approaches you pitch to slope because you have to maintain a precise path on a little needle - worry about that later). You never want to be holding continuous pitch pressures for any more than short transient conditions. You don't crank the trim wheel to make pitch changes (although you can) you make pitch changes and follow up with trim. This gets more and more important as the planes get heavier and the control forces go up.

Large turboprops are flown with power right up to the touchdown. Jets come off the power a bit sooner, and jets that are clean in landing config (generally those without slats) come off the power quite early - in the CRJ200, you go to idle at 50ft.

Answer 2

I’m assuming that you did your commercial work in a TAA C172 with little or no time in Piper airplanes prior to beginning multi engine training in a PA-44, correct? That might explain why flying the Seminole seems so different.

Most Piper singles and twins like a little bit of manhandling on final and during the roundout; not a whole lot finesse here. The PA-44, which is essentially a twin engined Cherokee Arrow, is going to probably fly a lot like its single engine cousin does. They are really power dependent and, once you pull the throttles to idle, they’re going to drop like a brick. John K points out some of the reason it the drag from the two essentially windmilling props, but again this is just a Piper retract thing.

As to aimpoint, you need to revisit your goals in the roundout: arrest your descent and place the airplane in the correct attitude for landing. Arrive at the roundout at the correct approach speed specified in the POH or no lower that 1.3*Vso to minimize float. Your instructor’s landing techniques are fine, though I would not say “throw out everything you learned about landings from a Cessna”; the techniques still apply but every airplane out there has its own specific performance quirks.

A more critical metric here is touchdown point and that’s dependent on how long the airplane will float in the flare. Try this: on your next pass in the PA-44, when on final, trimmed up and power set for Vref and on glidepath, aim for the first stripe on the runway to enter the flare over. Keep tabs on how many runway stripes the airplane floats over during the flare and note which stripe the airplane finally touches down on. Since each stripe is 120ft long with an 80ft gap between them, you can quickly determine the distance of the float and pick your aimpoint in front of it accordingly.

Remember, don’t reference your aimpoint based upon features in the cockpit, reference it based upon whether its moving in your field of view on final. If you're heading for the aimpoint it should be fixed in your field of view and only increasing in size.

Typically you will smoothly reduce power i.e. pull throttles back to idle over ~1-2 seconds just as you enter the round-out. This is a pretty good technique in Pipers and yields a smoother touchdown. Just be ready to pull back on the yoke as you simultaneously reduce power in the flare as the nose will quickly drop otherwise. Unless you’re flying a seaplane, don’t keep power in during the flare. It only increases the float and eats up more runway needlessly.

Answer 3

Read (and upvote) John K's answer. Some great experience there.

Some really important points:

1. Match approach speed with weight. Approaching too slow is "bad".
2. Use power to make plane "your favorite glider", with a comfortable, manageable glide slope.

Notice John's point about "clean jets" take out power sooner. Keep power in if you are very "draggy". This is what your instructor wants, a nice flat approach, and easy round out. If you are trimmed for speed and power on final, you should just be flaring after you round because you do not have enough power for level flight.

This is where thrust vs drag and gliding experience hits home. This is what you practice at altitude. If you find yourself floating down the runway at your power setting, go back up and find your min power for level flight (using the horizon as a reference) at the flare pitch you land at. Your power setting at landing will be less than this, practice will refine your technique, but it is much worse to be too slow than too fast when you round.

So don't worry about landing a little long if your runway allows for it, at first. It is ok to control your touchdown by easing out power as long as your nose is high enough to protect your nosegear. Good luck!

Answer 4

Flare at a relevant high level, then idle power slowly… Flare at a lower height, then idle the power quickly… I found it has really strong ground effect, it could drift a long distance if you keep power during flare. And we got G1000 system here, so sometimes i am in a new airport, i am gonna go to see the attitude to make sure that my real attitude is not nose wheel down, it is about +2.5~+. (Attitude indicator plays an important role here in Chinese pilot training…)