March 1999 Volume 42 / Number 3
What's new in aircraft safety?
Change comes slowly to general aviation, particularly in aircraft and associated hardware. Some would say that we move on a geological time scale, although measuring improvement by decade is probably a fair interval. How are today's aircraft safer than what was available one or two decades ago? We contacted some manufacturers to ask what they were doing to improve the safety of their products. This will not be an exhaustive listing and excludes avionics, which have been evolving rapidly. Electronics seem to mutate as fast as any virus, while some of the good old mechanical stuff is precisely that. It has stood the test of time, and changes much more slowly. But there is some good news.
Light aircraft piston engines are reliable — not as good as turbines, but then they don't cost as much as turbines either. GA piston engines are said to lag automobile engine development, but that is something of an apple-kumquat comparison. Car engines run at somewhere around 10 to 20 percent power on the highway. Airplane engines operate with the hammer down in takeoff, climb, and cruise. There are other areas where they differ and some notable experiments have failed to adapt auto engines on a large scale to small aircraft. Porsche and Mooney gave it a valiant attempt in 1987. Toyota tinkered with it (and may be coming back to try again), as have thousands of homebuilders, but aero engines operate in a vastly more hostile environment than their automotive counterparts.
Teledyne Continental is working closely with NASA on electronic engine controls and single-lever power controls (see "Airframe & Powerplant: Power to the Processor," November 1998 AOPA Pilot). This is where throttle, prop, and mixture all play together through one control — something the jet folks have come to know and love. Push for go and pull for slow, and the engine adjusts itself to the environment. With a single lever the pilot can't run the engine lean or rich, and that should contribute to a more stable operating environment and reduced work load. Less distraction is a safety advance. Cirrus, as an interim step, offers a combined throttle and prop control in its recently certified SR20.
Electronic displays of engine operating parameters are now common, to include cylinder head temperatures and exhaust gas temperatures (see "Pilot Products: JP Instruments EDM-700," p. 136). These provide pilots with a much more detailed look at what's happening in the engine. The displays provide a diagnostic capability that is well beyond the small single-needle gauges of old. New Piper's digital engine monitoring panel on the Malibu Mirage, Seneca, and Saratoga processes engine, electrical, and fuel data and provides an audible warning if anything is outside of normal tolerance. Mooney has new digital/analog gauges with annunicators as well.
Cessna has improved the engine instrumentation on its new piston line to make it more visible, changing from small rectangular gauges to two-inch-round dials. It has eliminated pressurized fuel and oil lines from the panel in favor of electric gauging. This should simplify working behind the panel and require less plumbing and weight. Flammable liquids in the cabin are not such a great idea and this removes that fire potential. Cessna also has added annunciators for a variety of undesirable situations.
The information age is now catching up with light aircraft as Teledyne Continental introduced its TCM Link network to provide direct online access on engine information to pilots, FBOs, and distributors. Each time your engine is serviced, the technician can check on outstanding service bulletins and research problem areas relative to your particular engine. Record keeping is a good discipline and follows what has been common in the turbine world for decades. It won't hurt the resale value of a well-maintained machine either.
Cessna and Lycoming teamed up to make a significant improvement in the new Cessna 172 and 182. They eliminated the carburetor and replaced it with fuel injection. As reliable as carburetors are, they cause dozens of mishaps each year. The AOPA Air Safety Foundation's review of general aviation weather accidents found that, during an 11-year period, more than 300 accidents were caused by carb icing. Many more probably went unidentified because the ice was gone when the investigator reached the accident site.
The phenomenon of carb ice dates back to the inception of aviation, and the only way to eliminate it is to get rid of the carburetor. The purist might say that we should train pilots better. No one will argue in theory; but in practice, humans foul things up in spite of their training. Why keep something that has a known propensity to cause accidents and increase pilot work load? Fuel injection on small engines is a significant step forward for safety.
New Piper recently added improved strobe lights and flashing forward recognition lights to make its aircraft more visible. Midair collisions involve from 20 to 50 aircraft per year, so a cost-effective approach such as lighting to make us more conspicuous is useful. I'd still like to see some type of rearward-facing lights, since many collisions involve overtaking aircraft, and in that circumstance there is only one pair of eyes able to see and avoid compared to two in a head-on situation.
Both New Piper and Cessna have improved their seats, seat belts, and attachments. Piper claims protection from a 25-g forward impact. Cessna has redesigned the seats, seat rails, and tracks to meet a 26-g stop. Inertia reel shoulder harnesses are now standard. It's a small change but welcome to all who have struggled with a constantly maladjusted belt. While we're on the topic of harnesses — they are one of the most important safety devices on board. Since the mid-1970s, all new aircraft have had them and they would be high on my list of safety improvements for retrofit. Granted, it isn't easy or cheap on some models because the attach points have to be fabricated and strengthened. Short of wearing a helmet, this is a great way of saving face — pun intended.
On aircraft certified under FAR Part 23, the cabin structural integrity and rollover requirements are higher than the grandfathered limits of earlier designs.
Most of the manufacturers are now offering low-fuel warning lights as standard equipment. With the amount of fuel mismanagement that occurs annually — more than 160 accidents in 1997 caused by exhaustion or starvation — this seems like a no-brainer. You can't buy a car these days without a yellow light to advise that a long walk is in your future if fuel isn't added soon. The addition of a low-fuel light isn't a complete solution but it will help the less determined pilot remember that engine silence is not golden.
Virtually all the manufacturers now offer internally lit instruments. The panel is much easier to see at night and is hundreds of lumens brighter than the single red bulb that used to pass for instrument lighting. While it may be a stretch to say that poor cockpit lighting is the cause of some night accidents, it could well be a factor. Dim lights certainly contribute to fatigue and eye strain.
Finally, most new aircraft are now equipped with annunciator panels. Idiot lights, as they are fondly referred to in automobiles, have been standard on large aircraft from the beginning. Perhaps designers felt that lightplane pilots were more adept at scanning instruments than are turbine operators. More likely, it was a cost issue. Pilots flying less than top-of-the-line equipment were left to pick up the quarter-inch needle movement that signified a dead alternator, lack of oil pressure, or a blown vacuum pump. All these items are potentially catastrophic, and it's a significant safety improvement to have better monitoring equipment.
Cessna, Mooney, New Piper, Commander, Raytheon, and others now offer dual vacuum pumps or standby vacuum systems to provide the pilot with redundancy in one of the most critical systems. Loss of attitude and heading indicators constitutes a genuine emergency in instrument conditions and while we are all supposed to be able to handle it, the record shows otherwise. Turbine aircraft usually have two of everything, and the FAA considers attitude so critical that a third attitude indicator with its own self-contained battery is provided to help jet drivers keep the dirty side down. Anyone flying much more than very light IFR should consider a standby vacuum system or backup pump as an essential retrofit.
More manufacturers are following the lead of the car industry and are building aircraft now in base VFR, standard IFR, and deluxe IFR versions to simplify ordering and standardize the production process. The packaging offer includes the usual convenience/vanity items such as cup holders and upgraded interior, but there are some work load reduction options as well. Mooney includes an autopilot as standard gear, as does Cirrus. ASF in its safety review of the Mooney found that the M20 was involved in about 20 percent fewer accidents than other comparable aircraft. We speculate that this may be attributed to the fact that virtually every Mooney built has a wing leveler or autopilot. For instrument pilots and long-distance VFR cruisers, this is a great energy saver and frees the pilot to manage the overall progress of the flight.
One of the most innovative safety features recently introduced is the whole-aircraft parachute that will be built into every new Cirrus SR20. Put simply, if the aircraft is in an untenable situation, the pilot can just pull the red handle and hold on. A 52-foot canopy will deploy, and if the SR20 is more than 600 feet agl, it will settle to the ground at about 1,500 fpm. That is a solid arrival. However, this technology is credited with more than 100 saves in homebuilts and ultralights, so the theory is promising for larger aircraft. Pulling the handle is analogous to using an ejection seat in a military aircraft or deploying airbags in cars. There may be circumstances in which the system will not save the occupants or may cause injury, so it's not an action that is taken lightly. After a midair collision, when pieces of the aircraft may be missing, the parachute seems like a good deal. Likewise, if a VFR pilot gets into the clouds and rolls into a graveyard spiral, it certainly beats the alternative. Single-engine IFR at night may also be more palatable for some. It will take a few years of actual experience to know whether the parachute makes a statistical dent in SR20 fatalities. However, Cirrus is to be commended for trying something significantly different in the safety arena.
The aerodynamics of the wings on the SR20 and the Lancair Columbia 300 are different as well. According to Cirrus President Alan Klapmeier, "We wanted to give the SR20 the most docile and controllable stall characteristics we could. Thus, the aircraft has considerable aileron and rudder control right into the stall. It will descend, but the nose is slow to pitch uncontrollably." As with all aerodynamics, there are tradeoffs. An aircraft with a very gentle and controllable stall may be lethargic in spin recovery. If the airflow is slow to detach from the wing, it may be equally slow to reattach if the stall is aggravated.
The FAA normally requires recovery from a one-turn spin in one additional turn. While Cirrus did spin the SR20, the manufacturer elected not to meet that requirement and offered the parachute as a last-ditch spin-recovery device in return for a very gentle stall. So, an inadvertent stall at low altitude should not develop rapidly into a spin, and with a modicum of skill the pilot should be able to recover. If the airplane spins at high altitude, the parachute may be needed, and spins at low altitude may be unrecoverable even with the parachut — just as in any other aircraft.
So, how do new aircraft compare in safety to models built several decades ago? On a theoretical basis, generally better. Improved seats and seatbelts, better exterior and interior lighting, better instrumentation, some minor engine improvements, and more redundant systems add up to a safer machine. Statistically, it's difficult to measure the exposure of new aircraft to older ones and say with certainty that all the new gear helps. With the exception of the Cirrus and Lancair Columbia, the airframes have changed little. The expense of reengineering, tooling, and certification is as daunting as the hard realities of aerodynamics and the inevitable tradeoffs. The old-guard airframe manufacturers have all had winning designs in the market. For the newcomers, the marketplace will vote soon. And while the safety improvements are real and worthwhile, it is the pilot who makes the biggest difference.