By David Jack Kenny
Prospective buyers who aren’t intimidated by the “experimental” designation may detect an attractive value proposition in amateur-built aircraft. Offsetting the absence of any crashworthiness standards are the potential to achieve higher performance at lower cost, plus vastly greater freedom to equip, configure, and modify the aircraft as its owner might see fit. Worth bearing in mind, though, is the fact that homebuilts are simply less predictable than certified aircraft. Even within a single design, different examples are apt to show far more variation in layout, workmanship, and handling than two Skylanes built 40 years apart—and the numerous updates and improvements that every older aircraft tends to acquire won’t have been evaluated as systematically. In light of those subsequent modifications, even the relevance of the initial flight-test results can’t be predicted with confidence. Unless the new owner receives transition training directly from the person who did the original flight tests and the machine’s remained essentially unchanged, that new owner needs to be aware that he or she has marched straight back into the flight-test regimen.
According to the current owner of the design rights, a “stock” Rand-Robinson KR-2—that is to say, one built and equipped precisely according to the original plans—enters and recovers from spins like most other low-wing light airplanes. But the KR-2 that took off from Shoshone County, Idaho, airport on Aug. 18, 2013, was not stock. The original engine, an air-cooled Volkswagen unit modified for aviation use, had been swapped out for a Continental A75. The Continental engine was a bit heavier—how much has been difficult to pin down—but that extra weight was placed at the absolute front of the airplane, where it would exert the maximum possible leverage in a spin. Unfortunately, spins were one of the maneuvers the airplane’s owner had decided to try that day.
Inquiries at the airport identified a practice area less than 10 miles west of the field, which is located in a valley at an elevation of 2,227 feet msl. The 67-year-old pilot turned on his in-cockpit video camera before taking off at about 7 p.m. local time.
We can be grateful that the video footage hasn’t been released. The description the NTSB’s factual specialist prepared for the accident docket is more than excruciating enough. After a series of maneuvers including steep turns and lazy eights, at an altitude of 5,800 msl (or about 3,600 feet agl), “the pilot pulled the throttle all the way aft … [and] pulled back on the stick while simultaneously pushing the left rudder to the floor of the aircraft.” Two seconds later, “the nose began pitching down rapidly as the aircraft yawed and rolled to the left.” One second later, “the aircraft was rolling left and was about 30 degrees from inverted. The vertical speed was increasing through 1,500 feet per minute.” One second after that, “the nose of the aircraft was nearly vertical down and the aircraft was spinning about the yaw axis to the left. The pilot began to release the left rudder and add right rudder…. The aircraft remained in a left spin for the duration of the flight.”
Early in the 42 seconds that remained to him, the pilot tried forward stick with the airplane pitched 50 degrees nose-down. It had no apparent effect. After about 15 seconds the engine quit, just about when the spin reached a steady state, completing three revolutions every two seconds with the nose pitched down 20 degrees. “Throughout the remainder of the flight, the pilot made a variety of control inputs including: (a) stick forward, (b) stick aft, (c) right rudder, (d) left rudder, (e) left stick, (f) right stick. The inputs were made in various combinations of rudder, forward/aft stick, left/right stick.” By the time the airplane hit the ground, the camera had recorded “about 25” complete revolutions in the spin. Motion stopped within two seconds, but the camera continued to record sounds, including “dogs, geese, and motor vehicles … As darkness approached, crickets were also recorded.”
We don’t know the extent of the pilot’s aerobatic training, but it probably wasn’t extensive. His logbooks weren’t recovered, but a medical application filed a year and a half earlier listed 305 hours of total flight experience. The certification information in the airplane’s records listed it as having initially been tested for controllability in wingovers, loops, and rolls—but not spins.
FAA Advisory Circular 90-89A, which addresses flight testing of amateur-built and ultralight aircraft, makes for sobering reading for those of us not familiar with that environment. Two provisions from the section on spin testing are particularly relevant:
During all spin tests, it is strongly recommended that the pilot wear a parachute and that a quick release mechanism to jettison the canopy or door be installed. If the pilot is unable to exit the aircraft because of the design restraints, it is recommended that intentional spins not be conducted even though the design has successfully demonstrated spin recovery.
If any modifications or alterations have been made to the airframe’s original design or configuration (e.g., adding tip tanks or fairings), it is not safe to assume that the aircraft still has the same spin recovery characteristics as the prototype aircraft. Spins in a modified aircraft should not be attempted without consulting a qualified test pilot and/or flight test engineer.
Given the pilot’s background, his choice of entry altitudes, and the lack of a parachute, it’s likely that he viewed the flight as spin practice rather than spin testing. He didn’t know or didn’t appreciate that this particular airplane had never been spun— meaning that there was no guarantee that that particular airplane could recover from a spin, whatever had been shown by the prototype. Caveat emptor can have terrible implications when the buyer isn’t sufficiently aware.
Transitioning to Other Airplanes online course
Essential Aerodynamics online course
Advisory Circular 90-89A: Amateur-Built Aircraft and Ultralight Flight-Testing Handbook