July 10, 2002 Transitioning to Retractable Aircraft

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by	R. Scott Puddy

About the Author ... R. Scott Puddy was an ATP, CFI, CFI-I, MEI who taught out of the Buchanan Field Airport (CCR) in Concord, California. Scott was type-rated in the Beech/Raytheon King Air 300 series but regularly flew a V35 Bonanza and practices law in San Francisco. On the morning of June 18, 2002, Scott perished doing what he loved: practicing aerobatics in a Yak-52, in the mountains of Brentwood, California. He contributed many articles about flying to AVweb in recent years and also worked as our features editor. His enthusiasm for aviation and his intensity in pursuing it were simply extraordinary. Even more extraordinary was his dedication to sharing his passion for flying with others, by teaching and writing. He touched a lot of lives, undoubtedly saved many, and his legacy of written words will continue to do both for many years to come. Scott's warmth, wit, and keen intelligence will be missed by all who knew him and worked with him.

If you have ever gone to the store for a pound of butter and returned with a quart of milk, a gallon of ice cream, a carton of eggs, a loaf of bread, a bag of potato chips, and a box of cereal — but no butter — you are a candidate for a gear-up landing. Who hasn't? Who isn't?

If stocking an adequate supply of butter is that important to you, the solution is simple. Purchase a pound of butter EVERY time you set foot in a store. If you develop and adhere to that regimen, you will never have to choke down dry toast. And that — the development of a regimen for the approach-to-landing phase — is the essence of training for the transition to retractable aircraft.

Regulations And Guidance

The applicable requirements parallel the regulations and guidance for high-performance aircraft discussed in my prior article. The FARs state in Section 61.31(e) that, before acting as PIC of a "complex" aircraft — one that has retractable landing gear, flaps, and a controllable-pitch propeller — a pilot must receive and log ground and flight training from a CFI in a complex plane. The CFI must determine that the pilot is proficient to operate a complex airplane and enter a one-time endorsement in the pilot's logbook to that effect. 

The guidance of Advisory Circular 61-9b,"Pilot Transition Courses For Complex Single-Engine And Light Twin-Engine Airplanes" should also be considered.  It sets forth a recommended transition syllabus that tracks the Private Pilot Practical Test Standards. Pilots who are stepping up from a C-150 to a C-182RG may require a little air work to acclimate to the larger plane; pilots transitioning from a C-182 to a C-182RG may not.  However, ANY pilot stepping up to a retractable should receive training on in-flight procedures to establish a fail-safe pre-landing regimen.

The Approach Regimen

The approach regimen serves several purposes. First, it establishes a habit. Once ingrained, habits are hard to break. That's why 12-point programs do such a good business. In the case of landing with the gear down, a habit is a good thing.

Second, a regimen establishes a norm. You wouldn't notice someone wearing a blue shirt on a crowded sidewalk unless everyone else were wearing white shirts. When white shirts are the norm, blue shirts are suddenly abnormal. They become noticeable. If you fly every approach using consistent power settings and configurations you will establish "normal" airspeeds and "normal" descent rates. When the day arrives that you attempt to fly the plane down to the runway with the gear up, you should detect that the airspeed and/or descent rate is abnormal. You will more readily notice that a discrepancy exists.

Third, the regimen can literally preclude you from landing unless the gear is extended. If you carry sufficient power during the approach and maintain approach airspeed, the airplane will not descend unless the gear is down. Until you can descend, you cannot land. Until you can land, you cannot land gear-up.

... for example ...

In a Bonanza, the landing regimen begins in level flight with 17-18 inches of manifold pressure. That yields around 130-140 KTS which is below gear speed but well above flap range. The flaps can't come down and the plane won't descend unless you drop the gear first. You extend the gear a half mile or so prior to the final descent point — mid-field downwind in a standard pattern — and your right hand doesn't leave the gear switch until the light turns green. While you maintain level flight, the additional drag brings the airspeed indicator into the white arc and you can lower the flaps. It's time for a GUMPS check and the descent to landing. The plane settles into a 500 FPM descent at 90-100 KIAS. It will decelerate quickly when you pull the power so you can carry 17-18 inches/90-100 KIAS/500 FPM right up to short final. When you get there it's time for the final gear check and, if the light is green, you can twist out the throttle and land.

After you land the airplane in this fashion a hundred times, you will become accustomed to seeing 90-100 KIAS and 500 FPM. If you look down and see 120 KIAS or 100 FPM the neurons in your brain will discharge. Something is abnormal. Something is wrong.

Many instructors advocate an intermediate gear check on the base leg. Others omit that because you don't fly a base leg for every landing. Using a base leg check for normal patterns and omitting it for straight-in landings — which are quite common following instrument approaches — requires you to alter your regimen. However, you will always begin your final descent at some point and you will always arrive at short final. The first thing/last thing gear check allows you to follow the same procedure for every landing, and that is how good habits are formed.

... but this is boring

The old saw is that flying consists of hours of boredom interspersed with moments of sheer terror. Sure, cookie-cutter landings are boring, but that's what we strive for. The hot dog approaches where you pull the power to idle abeam the numbers, slip it in, and squeak it on the numbers are one way to show off your piloting skills. A better way is to touch down with a load of passengers who are bored to tears and bewildered by the mere suggestion that anyone could discover excitement in an airplane. You can always express your individualism by wearing a blue shirt.

Whoops — No Green Light!

That would just about cover transition training for retractables if the light(s) were always green when you reached that line in your script. Unfortunately, that will not always be the case. You will have to troubleshoot an airborne gear system failure at some time or another and that is why transition training must include a comprehensive treatment of your particular system and its usual failure modes.

There are at least four basic types of gear systems installed in planes that the likes of us may have a chance to own and fly: manual, pneumatic, electro-mechanical, and electro-hydraulic.

... manual systems ...

The "Armstrong" manual extension/retraction system installed in early generation Mooney aircraft draws raves for its simplicity and reliability. The pilot raises and lowers the gear using a johnson bar, similar to the excellent manual flap system in Piper Cherokees. There is no requirement for electricity or hydraulic fluid. All it takes is a strong arm.

The emergency extension drill is very similar to the normal procedure. The pilot merely lowers the gear with greater resolve. Given the size of the johnson bar and its location in the center of the console, it is readily apparent whether it is in the "up" or "down" position. Unfortunately, the johnson bar arrangement had a certain...well...low-tech feel. Practicality gave way to panache and Mooney switched to an electrical system.

... pneumatic systems ...

Another oddball system that you may run across as the exodus of military trainers from Russia and Romania accelerates is the pneumatic system installed, for example, in the Yak 52. Air pressure extends and retracts the flaps and gear and applies the brakes — including differential braking for steering — all accompanied by vibrations and sounds that would be more befitting a steam locomotive than an airplane.

What the system lacks in finesse it makes up through its benign failure modes. There are plenty of indicators to tell you where the gear are and the emergency extension system is a snap. Both cockpits have gear position lights for each wheel. The gear position lights are backed up by three mechanical gear position indicators (barber poles). To guard against a failure of the primary air system, there is an emergency reservoir. Select gear "neutral" with your left hand, turn the valve with your right hand and the gear come down with authority.

Even more reassuring is the fact that Yaks are designed to land and taxi even with the gear retracted, although you'll lose a couple inches off the wood propeller blades. The main gear retract forward to a position close to but not inside the wing. That places them ahead of the plane's center of gravity. In the event of a gear-up landing, the plane becomes a tail-dragger, with an emphasis on "drag." The brakes will function normally, as will steering via differential braking.

Once the plane is on the ground with the gear retracted, it will even right itself. Select gear "down" and the cylinders will be pressurized. If you station a colleague at each wing tip and one at the tail, with a little "see-sawing" back and forth, the gear will extend with the plane sitting on them. Try that in a C-182 RG.

... electro-mechanical systems ...

For better or worse, most of the systems we fly are more "refined" and many of them have failure modes that would mitigate against even attempting an emergency gear extension under certain situations. The transition training should identify those circumstances and you should be prepared to belly in when they exist.

Beechcraft's electro-mechanical gear system is one example.  The advantage of an electrical gear system is that there are no hydraulics involved so you don't have to worry about leaks, worn cylinders and the like. The downside is that the most likely gear emergency will involve a catastrophic failure of the electric system — in which case you will probably be confronting a host of other problems as well.

The emergency extension procedure requires you to turn a crank approximately 50 turns to fully actuate the jack screw. The crank is located behind the co-pilot's seat and you pretty much have to place your head in the co-pilot's lap to reach the crank.

From both an ergonomic and a physiological perspective, that is not the ideal position from which to scan the flight control instruments. If you are VFR, have a qualified co-pilot, or have a functioning auto-pilot, the emergency extension procedure works. If you're single-pilot IFR, the panel is dark, and VFR is out of range, you should count on landing gear-up. It's better to contact the ground with the belly than with the spinner.

... electro-hydraulic systems

In the vast majority of cases where our landing gear move, hydraulic fluid is doing the pushing and electricity is supplying the energy. That means you have a gear emergency in the event of a problem with either of the two systems. That, in and of itself, is not overly troublesome so long as the failure mode is recoverable. In some cases it is. In other cases it isn't.

Piper did it right in their late-model single-engine retractables. An electrically powered reversible pump supplies hydraulic pressure to either the gear-up lines or the gear-down lines. After the gear has fully retracted and system pressure has developed, a pressure switch shuts off the pump. When pressure decreases, as it will in time, the pump cycles on and off to maintain system pressure and keep the gear retracted. Hydraulic pressure is the only thing keeping the gear from free-falling into the down-and-locked position. In the event of a loss of hydraulic fluid, gravity will extend the gear. If an electrical failure occurs, the pilot can release all system pressure by depressing the emergency gear extension switch on the center console. It's a two-finger, five-second operation.

Cessna's retractable gear system has proven more problematic. In discussing the C-182 RG model, Aviation Consumer's Used Aircraft Guide reported that "[t]he litany of problems with the gear chronicled by the SDRs almost defies description." Although Cessna's system is similar in concept it is quite different in application because the high-wing design required that the main gear retract rearward into the fuselage. The tortured path that the gear travel to accomplish that calls for a more complex system of actuators. More significantly, the fact that the gear retract rearward means that they must travel forward into the air stream in order to extend. Gravity will not accomplish that so Cessna installed a hand pump to pressurize the gear-down circuit in the event of a powerpack failure. The hand pump works fine so long as the hydraulic system is intact. However, if the hydraulic fluid has been exhausted, the pump can't do its job.

Mike Busch wrote an excellent article suggesting that efforts to avoid landing gear-up can be more dangerous than executing a "routine" gear-up landing. I concur. Twenty years ago I started transition training in a C-172 Cutlass RG. My instructor claimed that there is no excuse for ever landing gear-up. He asserted that there is always a way to get the gear down and regaled me with stories about pilots hanging out the side doors of Cessnas and swinging the gear forward using the tow bar while their passengers held them by their belt loops. The memory makes me cringe. Once you've been all that you can be, it's time to land the plane on its belly, walk away, and call your insurance agent. Read Mike's article for a thorough and compelling discussion of that topic.

Fuel, Time & Troubleshooting

The troubleshooting process will vary for each system. Suffice it to say that the absence of a green light doesn't necessarily mean that the gear isn't down and locked. In more cases than not it is a problem with the light, the micro switch or — in the case of Pipers — something as mundane as having the panel lights switched on in daylight. Whatever the process is, you will want to have adequate time to think it through so that you won't be rushed into making a bad decision.

Your typical government-funded study would conclude that the vast majority of gear-related accidents occur near the termination of flights. When a failure does occur, you will most likely discover it during the approach-to-landing phase after having consumed all the fuel you allocated for takeoff, climb and cruise.  Your pre-flight fuel planning will determine how much time you will have to troubleshoot the problem. More fuel means more time and "more" is better. The potential for a gear problem is an excellent reason not to push your reserves. 

Fly safe.