Saturday, May 9, 2009

Retract endorsement a complex affair

Second and last flight for my retractable undercarriage endorsement, two days after the first one. I spent a full evening in-between writing down lists of checks and actions for each leg of the circuit, and drawing flow patterns that take me in a sequence through each gauge or control required at any stage of the circuit.

This proved quite useful, although there is as always a big difference between rehearsing things at home and doing them for real in the cockpit. Plenty of things come in the way, such as other aircraft in the circuit, that pesky instructor in the right seat, or the tower controller. Not even talking about the effect of stress on cognitive abilities. It is a well known fact that one only has half a brain left when flying an airplane, which makes planning and rehearsing beforehand all the more important.

So we did about 7 or 8 circuits in the Arrow IV on runway 29L. It's true that because of the T-Tail one has to pull harder on the yoke to get the airplane to rotate or flare, even with the trim slightly aft of neutral. The accepted explanation is that because the stabilator is outside the propeller slipstream, it becomes less effective at low speed. All other things being equal.

But are the other things really equal? The moment arm between the center of gravity and the stabilator is longer in the T-Tail Arrow IV compared to the Arrow III, which should help. Maybe the surface of the stabilator is smaller. Or maybe the reason for the design change is to be found elsewhere. According to this article on the Arrow IV, in 1979, Piper made a controversial design decision, opting to equip many of its airplanes with trendy, fashionable T-tails. So it may all boil down to a marketing fad in the end.

This turned out to be a lot of work in the circuit, which really stresses the importance of having sequences of actions and checklists memorised. I forgot quite a few times to touch the brakes before retracting the gear, which is not good since the wheels keep spinning inside the well, which may create some wear on the tires. Olivia had to use the Law of Intensity on me so that this particular aspect of operating a retractable undercarriage would stick with me, and it worked.

I made a conscious effort to slow down in the circuit to maintain separation with the other slower aircraft. It's actually a nice way to measure the ground covered since I started learning to fly in the C152 at Redcliffe two years ago: I am no longer the slowest guy in the circuit.

In the last circuit Olivia pulled the circuit breaker of the landing gear pump on me. I noticed that the three green lights didn't light up. She was happy I noticed, pushed the circuit breaker back in and asked what I would have done otherwise. I said I would have flown to the training area to perform the emergency landing gear extension procedure, which was the right answer. Olivia also insisted I verbalise out loud "three greens" as part of my pre-landing checks.

On each landing I tried to not float as much as on the previous one. The airspeed on final recommended by the club is 80 knots, while 1.3 Vs is 71 knots. The extra 9 knots add a lot of energy to the airplane, which also means that as it slows down from 80 knots it crosses a region of lower total drag, which does not help with slowing down further obviously. This was actually the topic of a recent training tip in AOPA ePilot newsletter.

We taxied back and Olivia put a new stamp into my logbook with an endorsement for the P28RT type, where R stands for Retractable and T for T-Tail. So I am now allowed to fly "complex aircraft" solo. Complex aircraft refers to aircraft with flaps, variable-pitch propeller and retractable undercarriage.

It's a very impressive term that conjures up a picture of aircraft mightier than a Piper Arrow. If I wasn't married I may even be tempted to use my newest endorsement in order to impress girls. Not unlike that scene from a movie we all know.


Vincent, from said...

Nice post, congrats for the endorsement. I like the "assigned altitude" gadget in your cockpit photo. Do you actually use it ?

I always believed that the "T" in PA28RT was for "Turbo". There is room to learn everywhere...

Julien said...

I do not use the assigned altitude gadget too much, no. I think I would use it if I spent more time in controlled airspace or if I flew IFR. I know which altitude I should be at because it's on the flight plan if I'm outside of controlled airspace, or in controlled airspace I write clerances down on a piece of paper.

Thanks for pointing out the mistake with the PA28RT... You're actually right. The model is officially PA-28RT-201T Turbo Arrow 4 for example, but the official ICAO 4-letter type designator is P28T hence my confusion. I didn't fly the turbo model, so for me the correct type designator is P28R.

Chad said...

Hey good post and congrats. Its a little different here in Canada, we don't have a complex endorsement. In my training I went right from a C-150 to doing my multi-rating in a Twin Comanche.

Why does the flight school recomend 80 kts if 1.3 Vso is less then that? It seems to me sometimes flight schools have a tendency to over-inflate the margin for safety to a point where it makes things more difficult. Regardless of school policy, you'd definitely make it easier on yourself to fly the approach at 1.3 Vso, and it certainly wouldn't compromise safety in any appreciable way, unless you're dealing with +/- 15 kts of wind shear.