October 2007 Volume 50 / Number 10
Safety Pilot: Light sport design
Bruce Landsberg is the executive director of the AOPA Air Safety Foundation.
Only Rip Van Winkle could overlook the buzz surrounding light sport aircraft (LSA) these days. It's nice to remember that new primary training aircraft did not always cost $250,000! While some LSAs will be used for personal recreation and perhaps occasional transport, the majority will likely wind up as primary trainers. When Cessna formally announced the SkyCatcher, the company took hundreds of deposits from flight schools looking for ways to offset the high cost of getting new pilots started.
Cirrus Design also did very well with the new SRS. The new designs are bringing innovation, but we should remember some past lessons.
With the current and proposed flock of LSAs, you can pick your vehicle: high wing, low wing, sleek new design, classic nostalgia, steam gauges, or glass. There are currently more than a dozen companies engaged, and not all will survive as the market decides which manufacturer does it best.
Having flown a few of these machines and given a lot of instruction in trainers, I'll offer some opinions on what would make a great trainer; please feel free to chime in at any point. Many of these comments will tie back to safety as an essential underpinning of good design. Early in my career, I got to know the Cessna 150 and 152 very well, both as a student and later as a CFI. In its prime, the smallest Cessna defined training aircraft, with more 150s and 152s guiding more students into the sky than all other makes combined. They were inexpensive to buy and operate and easy to fly.
Let's start with wing location. High or low, it really doesn't matter, but what does matter is cockpit visibility. Trainers spend a lot of time in high-density airspace. It's usually not in Class B, where everything is under positive control — often with collision avoidance equipment and two sets of eyes. "Collision" airspace is statistically shown to be the highly dynamic environment of nontowered airports and their environs. Aircraft structure that blocks the view is problematic. Low-wing designs generally have the edge here, but it doesn't have to be that way. The Cessna Cardinal (AOPA's sweepstakes aircraft for 2007) and the not-quite-in-production Symphony have decent high-wing visibility because the pilot sits forward.
It isn't just wings that get in the way either. Fat door and windshield posts also are troublesome, as is instrument panel height. The high and mighty panel may have started in the bizjet community because there was a lot of equipment that needed to be crammed into the available space, and at high altitudes, where pressurization is an issue, structure is stronger than glass. Early Lears had narrow windshield slots. Cessna broke that mold with the Citation, which continues to have excellent visibility. Because we are teaching physical airplane handling skills, not instrument flying, and the vast majority of these LSAs will operate under VFR, manufacturers should put the emphasis on see and avoid, not instrumentation.
The 150 didn't have great visibility, especially compared with the new bubble canopy designs, but you could peer around the wing root. It was great exercise for the abdominals. At one point Cessna lowered the seats, ostensibly to give taller pilots better headroom and to improve the view out the side windows, but then the panel loomed large and forward visibility went down. Those of us of average height, or below, resorted to carrying pillows — Cessna needed to lower the panel a few inches as well if this modification was to work as intended. Keep the panel low.
The 150's side-opening windows were a huge benefit on hot summer days. Proving that nothing is ever easy, the sleek new bubble canopy machines were probably designed in cold country. I'd ask the manufacturers to send an engineering team to Phoenix or Miami in mid-summer to fly in the low-altitude haze and turbulence in the midday hours. That's training airspace, where the flight never gets to the cool cruising altitudes. On a cross country at least, the sweat will dry before facing the furnace again on descent. CFIs and students spend entire flights in the hot box. We haven't yet mastered inexpensive or lightweight air conditioning, so airflow is critical. A comfortable training environment will help attract more new students, but in the interim, how about some really good vents and powerful fans?
The landing gear on the new trainers should be hell-for-stout and easily repaired because it will get a workout as new pilots perfect the perfect arrival. More than a few landings go awry, and the quick fix is essential for insurability and cost containment. The Piper Cub did this as well as any with the low-tech bungee cord arrangement. It sometimes put more than a spring in your step, or should I say bounce per ounce, but maintenance was low. Cessna's spring steel gear is legendary as well — it's hard to break a steel bar. I can personally vouch for its strength.
A few other items for ease of maintenance, before we leave the undercarriage, would include quick-change brakes and tires. These are rapidly consumable items in the training world, where some aircraft log more takeoffs and landings in a few weeks than some high-end cross-country machines execute in a year. Forget the expense of wheel pants, or make them optional for the few who buy these aircraft for personal use. For the reasons above, good preflights demand an unobstructed view of the stopping parts and tire rubber. Most flight schools just put the pants in storage.
The engine must be robust and easy to work on. In our flight school, the 150s were getting 100-hour inspections almost monthly, so access to spark plugs, oil fillers, filters, and drains with a quick opening cowling is more than just a nicety. Any operator with high utilization would probably trade a bit of acquisition cost against the constant hassle of prying apart cowlings with multiple fasteners to get at the essentials.
Kindly let carburetors go away. Yes, those engines are easier to start, but we still have quite a few carb ice accidents, and it's easier to change design than human nature. Yes, it's in the checklist and pilots are supposed to know, but slip-ups occur regularly.
Wing design should be friendly and docile. The Piper PA-38 Tomahawk had an aggressive stall-and-spin-recovery profile that, while meeting certification standards, had a significantly higher stall-spin accident involvement than other trainers. While we're discussing high angle-of-attack operations, how about including angle-of-attack indicators as standard? That's the subject of an upcoming column, but we could use some old technology to fix an old problem.
Flaps are pretty much dealer's choice as long as they have a reasonably high deployment speed; either manual or electric is perfectly fine.
Moving to the instrument panel, a good annunciator system that backs up the gauges on oil pressure, the electrical system (if any), and a bulletproof low fuel warning system will reduce injuries and dollars lost. Humans are lousy monitors, and flashing lights are far more effective in notification than small gauges. As for glass or steam instrumentation, that's personal preference, but if glass is the choice, it must be truly daylight readable. Some of the displays are not readable in direct sunlight. Obviously, reliability should be top-of-mind. The new pilot who chooses to go beyond local VFR and short cross-countries will get to the zoomy IFR stuff soon enough and should make the transition without much trouble.
Finally, there are the hard-core safety items. While it's not a happy thought, there will be crashes, and well-designed safety features are a good long-term investment. There should be no sharp edges or protrusions (knobs and switches) in the cockpit. Energy-absorbing seats with four- to five-point harnesses should be considered essential. If there's a canopy, there should also be some sort of roll protection to keep pilots from losing their heads if the aircraft happens to invert on landing. Parachutes and airbags are in vogue, and, finally, some basic fire protection would be a good investment. Frangible fuel lines and check valves are not very expensive to build in from the beginning.
This safety focus may not appeal to some who just want to go fly and have a high risk tolerance, but many potential new pilots, their spouses, and their families are keenly interested in the safety equation. It will help to sell aviation and it will save lives.