As part of its ongoing safety efforts, LOBO has convened a Safety Working Group to address 235/230/360 landing accidents, which have been trending upward recently. The following is an email exchange that occurred between three seasoned 320/360 fliers incident to an exhaustive review of available accident data. Jay Elliott is a retired Marine fighter pilot, and served as a test pilot with the Navy Test Pilot School at Naval Air Station Patuxent River, Maryland. He starts the thread discussing his observations about the unique landing characteristics of the Lancair 320/360. Jay was joined by Chris Zavatson, a mysterious engineer who works the dark side of aviation, has flown the 360 he built for more than 20 years and is a very experienced 320/360 inspector, and Bill Harrelson (who needs no introduction), with 2000+ hours experience in his 320. Jay’s comments are in black; Chris’s are purple; and Bill’s are in blue.
Jay: I was surprised by the relatively large number of accidents involving gear up landings and collapsed gear, but not by the number of those involving abnormal runway contact. I have no way of knowing if there is a structural problem with the landing gear, but based on a number of less-than-perfect landings in my airplane (both by me and during training flights) it appears to be pretty sturdy. However, I can think of a few possible causes of landing gear problems not related to poor checklist and verification discipline: There is a problem with the landing gear hydraulic system where the pump does not come on and power the gear down and locked when the gear switch is put in the down position (Chris Zavatson can explain in detail).
Chris: There is a failure mode where the pump is energized for a fraction of a second and then shuts down. I have a section that describes the details of how this works in my hydraulics paper online. While the dump valve will get the gear going again, the proper fix is to adjust the low-side pressure switch. I have tried to get the word out on this issue over the years, even making of a video showing the failure in action. Pressure gauges in the cockpit help identify this failure mode.
Jay: This situation is easily rectified by momentarily opening the hydraulic bypass valve to relieve up-side system pressure, but many pilots do not know this. The gotcha is that placing the gear switch in the down position does not guarantee the gear will go down, which means if the pilot does not verify three green gear indicators he or she could land gear up with the switch in the down position.
Chris: I don't understand why GUMPF has not caught these system failures. Perhaps that should be more ingrained in folks.
Jay: To get a down and locked indication when lowering the gear with the emergency system the air strut on the nose gear must have enough pressure to overcome air loads as well as any friction/binding. Checking emergency extension on jacks during condition inspections will identify binding problems, but does not verify the air strut has sufficient force to overcome air loads on the nose gear; it must be checked in the air. I check mine about every three months at 100 KIAS since if I get a safe indication at that airspeed I know it will work at the recommended 87 KIAS. Many pilots do not seem to know that an airborne check is required, and I have found two airplanes where the nose gear did not extend during an airborne emergency gear extension check, and the air strut had to be replaced. A landing gear component failure can occur as a direct, or indirect, result of bad landings, which can cause one or more gear to collapse. A direct result is obvious, but by indirect I mean cumulative stress fatigue from many "not so good" landings.
Chris: I haven't actually seen fatigue type damage from repeated less-than-ideal landings, however maladjusted hydraulics have bent and stretched parts to failure over time. Over-center links are 2024 aluminum, which will stretch a long way beyond yield before letting go. The broken links I have seen exhibit this long stretching consistent with hydraulic force applied to improperly adjusted components.
Bill: I agree. The 235/320/360 gear systems are quite robust and will withstand a fair amount of abuse from “normal” bad landings.
Jay: Before I get into landings specifically I need to discuss stalls. As you know I am a firm believer in stalling the airplane. I want to find out—at a safe altitude under controlled conditions—what the stall characteristics are before I inadvertently find a problem close to the ground. I've stalled my airplane many times, as well as every Lancair 2- and 3-series aircraft that I have flown. The stall characteristics are pretty consistent across the entire series. The idle power, landing configuration stall (which is important to the landing discussion) is characterized as follows: Control is adequate in all three axis (the airplane feels like it is flying even when stalled); there is minimal stall warning consisting of very light buffet 3-5 knots prior to stall; the stall itself (ball reasonably centered) is characterized primarily by a high sink rate (>1000 ft/min) with mild pitch and roll oscillations.
Bill: My experience here has been somewhat different. I always demonstrate the high-sink-rate-at-low-speed condition that Jay describes, but I do not consider the airplane to be stalled in this condition. Unless you’re looking at the VSI, this condition is almost unnoticeable at altitude, and in my opinion has led to some landing accidents. The high sink rate only becomes visually obvious as the airplane nears the ground, when the natural, but incorrect, reaction is to pull up to arrest the sink rate. Since the airplane was already on the edge of a stall, this results in an immediate stall break. I too have stalled most, if not all, of the two-place Lancairs that I have flown. I have found that if the stall is taken to a full break it will result in a sharp wing drop. This MUST be corrected with considerable alacrity by opposite rudder as well as forward stick.
Chris: Consider that many wings were not built perfectly symmetrical and thus have less than ideal stall characteristics.
Jay: We discussed possible causes of landing accidents on the phone, but I want to provide some more thoughts. Based on experience flying and conducting flight training in my 360 there are Lancair 2- and 3-series pilots who have had not-so-good landings and those who will, with the degree varying significantly. I will try to explain what I think are the causes below: Pitch control motions and forces are much less than most airplanes, and the short period response is quick, i.e. the airplane responds very quickly to pitch control inputs. These characteristics contribute to a tendency to over-control (PIO) the airplane in pitch, particularly in high-gain situations such as flaring in gusty or turbulent winds. This can easily result in hard touch downs. Aileron and rudder control are just adequate, which means there is little margin for error in crosswinds, particularly gusty crosswinds. The Lancair handbook says the crosswind limit is 20 knots, which means that is the maximum a Test Pilot demonstrated (I try to avoid anything in excess of 15 knots, particularly if gusty). Touchdowns with lateral drift are not uncommon in crosswinds, and fuel asymmetry (downwind wing heavy) can exacerbate the problem. Therefore, control characteristics can contribute to hard landings and landings with lateral drift, both of which put abnormal loads on the landing gear.
Bill: I agree. Once a pilot is used to, and comfortable with, the rapid pitch response most actually like it. I do.
Chris: Same here; I prefer the responsiveness. It demands skill recalibration for pilots used to more sluggish handling. While researching aircraft stability I came across a study that looked at accident rates as a function of stick force/speed stability in certified GA aircraft. The 2- and 3-series Lancairs are twice as sensitive as the accident-prone GA model that did poorly.
Jay: The Lancair community has this idea that horrible things will happen at slow airspeeds, so pilots tend to fly fast in the pattern. I fly (and teach) a pattern airspeed of 80-85 KIAS, which in my airplane is 1.3 VSO, but there are guys flying 10-20 KIAS faster. This means they arrive in the flare with way too much speed. The pilot must slow the aircraft below 70 KIAS to get into the proper attitude for a main gear first landing (flaps down), which means the pilot is floating down the runway bleeding off airspeed, fighting gusts, crosswinds, etc. If the airplane is landed too fast it touches down on the nose gear, which results in a "bounce" (actually what happens is the nose hits followed by the mains, which increases the angle of attack and the airplane starts flying again). The natural tendency of the pilot in a bounce is to push forward on the control stick (Chris: Is this true, or is the pilot simply out of phase with the plane?) which immediately removes the increased angle of attack (and lift), and the airplane hits the ground nose-down, harder. This may break the nose gear or result in another bounce, etc.
Bill: I agree here if the “pattern airspeed of 80-85 KIAS” is referring to the over-the-fence speed. Elsewhere in the pattern (downwind and base) I am a good bit faster.
Chris: I am a proponent of 1.3 VSO for over the fence speeds, but I do carry speed on down wind. My target is to slow to 120 abeam the numbers. Yes, some enter the round-out way too fast. Legacy drivers have been taught that way for some time now for unknown reasons, which burns up all kinds of runway. Just for reference, my numbers: Pattern entry: 140-150 Abeam the numbers: 120 All maneuvering: 90 (~2Gs available) Short final: 80 (unless heavy, gusty etc.) Touch down: 55-65 (deeper flare if calm)
Jay: Attaining the proper landing attitude requires the pilot to increase the pitch attitude in the flare to the point where it is impossible, or nearly so, to see the runway over the nose. There is a reluctance to do this, but even when done correctly it forces the pilot to judge flare height using peripheral vision, primarily out the left side due to side-by-side seating. This has two effects: a) a tendency to flare high and b) drift toward the left side of the runway (not sure I know why, but it is pretty consistent with pilots new to the airplane). Since proper landing attitude is achieved near stall speed it is easy to slow into a stall while trying to make a smooth touch down (this is where the stall discussion above comes in). The airplane feels like it is flying (minimal stall warning is easily masked), but a high sink rate is developing, which combined with a high flare will result in a hard landing. If hard enough, or combined with lateral drift, wing low, etc, this could collapse or damage the landing gear.
Bill: This paragraph contains what I believe to be one of the most important and useful pieces of information that a new Lancair pilot needs. The geometry of the airplane is simply different from any other civilian airplane with regard to eye position in the fuselage. In a Cessna 182 for example, the pilot’s eye is about 25% back from the nose and considerably higher than the top of the cowling. A fairly nose-high attitude can be held without compromising over-the-nose visibility. The 235/320/360 airframes have the pilots eye at the 50% point and, due to the semi-reclining posture, just a few inches above the cowling. In even a “normal” flare attitude compromises the pilot’s over-the-nose visibility of the runway. Visibility can likewise be compromised when rotating for takeoff, especially with early rotation such as with a soft-field takeoff. I always teach that the pilot needs to consciously redirect his vision to the left of the nose before rotation and before flare. I suspect that several of the landing accidents that I have reviewed might have been avoided with this technique.
Chris: Lancair used to teach this by having students fly down the length of the runway at 6" in the landing configuration with minimum power. Another problem I’ve observed is starting to round out too early and bleeding off speed too early. Jay: To sum up this long discussion, in my opinion, the Lancair 2- and 3- series aircraft are different from most light airplanes. Landings, in particular, demand a skill set that many first-time (and non-current) Lancair pilots do not possess. Gusts and crosswinds can make it difficult for even an experienced pilot to make good landings. Again in my opinion, flying the Lancair 2- and 3-series should be treated like flying a military airplane, training before first flight and regular currency. If a pilot is going to spend the money to own one he should be willing to spend the money to get training and fly fairly regularly.
Bill: I absolutely concur. I find it amazing that people will argue otherwise. In accident pie charts the 320 and 360 are usually shown separately. In reality these are the same airplane. If we combine these two entries in the pie chart, this airframe has a much worse record than the others. Training from a Lancair-experienced instructor could have, in my opinion, prevented many of these accidents. Yet, because it is at the lower cost end of the Lancair spectrum, resistance to training is greatest here.
Chris: Another variable to consider is original vs. MKII tail. These are really two different airplanes in terms of natural stability, and thus pilot work load. The MKII handles more like a 'normal' airplane based on FAA-defined characteristics. The Australians and UK authorities would not allow the original tail to be registered after they had some landing mishaps and a government test pilot did a qualitative flight evaluation. Lancair quickly came out with the MKII tail. There is unfortunately no way to tell what the impact on landing accidents has been.
Jay: I agree with almost every comment. I also like the way the 2- and 3-series fly, feels like a fighter, but guys coming from other small airplanes, transports, etc, have problems initially with control inputs, which is why training and currency are important. My only disagreement is with pattern speed, probably due to my Navy/Marine background. I configure on downwind to be on speed and trimmed at ~85 KIAS before I turn base then fly 80-85 KIAS all the way to the flare, using power to control sink rate. To me, this seems a much simpler pattern with plenty of margin above stall, even in a 30° bank. I guess I have never really stalled the airplane since I have never seen the wing drop, but the nose-high attitude and sink rate tell me the airplane is no longer flying even though it feels controllable. I have found I can control my airplane, flaps down, at +/-45 KIAS with about 20 inches MAP, which is the power required to stop the sink rate. However, it is not a useful maneuver due to the extreme nose high attitude and the fact that the rudder is effectively against the stop.