Gavin Grimmer
The Safety Board recently learned that in 1979, following a fatal stall/spin training accident in a PA-38-1 12 in Sweden, the National Aeronautics Board Investigation Commission of Sweden conducted a PA-38-112 flight test program. The purpose of the program was to study the low speed, stalling, and spin characteristics of the airplane. Two production airplanes were used, one configured with two stall strips and the other configured with four stall strips. A report on the flight test program concluded that after performing more than 60 stalls, PA-38-1 12 stall characteristics did not meet the 14 CFR Part 23 certification requirements for wings-level stall characteristics. Section 23.201, “Wings Level Stall,” states that wings-level stall characteristics must be demonstrated by slowing the airplane “until a stall is produced, as shown by an uncontrollable downward pitching motion of the airplane.” However, the test report concluded that the PA-38-112 did not exhibit the conventional nose-down pitching moment at the stall, regardless of stall strip configuration. Instead, stalls were characterized by a roll disturbance without pitch change.
In addition,the report concluded that the airplane did not meet the 14 CFR Part 23 requirement for stall warning. Section 23.207, “Stall Warning,” states that a clear and distinct stall warning must begin at a speed exceeding the stall speed by at least 5 knots. The Swedish program found that the stall warning horn “is engaged too late, approximately 2 knots prior to stalling with full flap, and 3 - 6 knots prior to stall without flap.”
Based on the findings in the Swedish flight test report, the Safety Board believes that the FAA should expand the upcoming PA-38-112 certification flight test program to include the following: (I) section 23.201 wings-level stall tests, to ensure that among other requirements, the stall is defined by a downward pitching motion of the airplane, and (2) section 23.207 stall warning tests, to ensure the stall warning horn activates at least 5 knots before stall.
PA-38-112 Flat Spin Mode
Most airplanes spin with the nose pitched down below the horizon. However, if the nose of the airplane begins to rise, a flat spin may develop. FAA Advisory Circular 61-67B, “Stall and Spin Awareness Training,” states that a flat spin is characterized by a near-level pitch and roll attitude and that recovery from a flat spin may be extremely difficult and, in some cases, impossible because airflow disruptions prevent the flight control surfaces from effecting spin recovery). Section 23 221 states that it must be impossible to obtain unrecoverable spins with any use of the flight or engine power controls either at the entry into or during the spin. However, during the Board’s review of PA-38-112 accidents/incidents, the Safety Board learned of several incidents in which unsafe, flat spins have been encountered in the PA-38-1 12.
PA-38-112 Flat Spin Incident Accidents
The Safety Board obtained a videotape of an October 1979 flight conducted by a NASA test pilot in a rented PA-38-112. The airplane was neither modified by NASA nor was it instrumented, as the flight was performed solely to familiarize the pilot with the airplane's spin characteristics. The flight was videotaped using a ground-based tracking camera at NASA's Wallops Flight Facility, and pilot comments were recorded via a VHF radio communications link. The videotape shows a series of 12 spins using various entry and recovery techniques. One maneuver documented by the videotape was a right spin with an attempted elevator only recovery. After several revolutions, the nose of the airplane began to rise. The test pilot immediately terminated the test and recovered the airplane. He stated that he "went ahead and recovered that one manually because it looked like it was beginning to flatten . He later stated, "It surprised me. In a test aircraft, that's often an indication that there's something we don't understand, and would likely want to investigate.” The pilot involved is well respected throughout the industry for his experience in the spin testing of general aviation airplanes. In addition, the former Piper chief test pilot interviewed by Safety Board staff in January 1997 described a PA-38-112 "flat spin" that he experienced in 1983. He stated that during an intentional spin, after approximately 2 turns, the nose started to rise to a more level pitch attitude, the rotation rate increased, and the spin "went flat." He said that even with full recovery rudder and elevator control, the "flat" spin continued for at least two more turns; then the nose slowly dropped and rotation ceased. He described the experience as "frightening. I didn't think that it was going to recover."
In April 1991, an FAA inspector from the Rochester, New York, flight standards district office was administering a check ride to a flight instructor from a 14 CFR Part 141 flight school in a PA-38-112. The FAA inspector had about 13,500 flight hours and had served as an aerobatics instructor; he had reportedly performed numerous spins in at least 15 different airplanes, including many spins in the PA-38-112. As part of the required check ride maneuvers, the inspector asked the candidate to perform a rate 1 turn spin to the right at an altitude of 5,000 feet. The candidate placed the airplane into a spin, however, the nose began to rise and a flat spin developed. According to the inspector, the candidate immediately attempted to recover from the spin using the recovery procedures described in the airplane flight manual, but the airplane continued to spin. The inspector then took control of the airplane and described moving the flight controls to maximum deflection with no response. In desperation, the inspector released his seat belt, pulled himself fully forward against the instrument panel, and instructed the other pilot to do the same (a maneuver which the inspector credits with saving their lives). After several more revolutions, the nose of the airplane dropped and a recovery was effected. Control of the airplane was regained less than 1,000 feet above the ground. Upon landing, the airplane was immediately inspected. No discrepancies were found and it was determined that the flight control rigging, weight and balance, and configuration of the airplane all complied with the airplane certification.
The outcome of this forth-coming re-evaluation of the certification tests were, in my opinion, wreaking of a cover-up, and I don’t recall ever seeing or hearing of any further modifications to the PA 38-112 to correct this ‘problem.’ To be fair, I don’t know of any PA38 accidents in NZ attributed to this stall/spin scenario.
I must add, that our Aero Club operates five of these aircraft and one now has in excess of 17,000 hours. We have found them to be a brilliant trainer and have never had even an ‘incident’ from stalling/spinning that I know of. They have proven to be a very robust, and reliable trainer.
In 1982, spinning was taught (mainly out of tradition) for a Pilot’s Licence (PPL) (until about 1983) but in today’s environment, it is only a requirement for an Instructor’s Rating.
I checked with NZ Aerial Mapping to see if they had any aerial photos of the Hinua Ranges, at a date as close as possible after the disappearance. For some reason I thought they only had them of the main eastern block of the Hinua Forest area, so I thought it may be prudent to check them anyway When they arrived, they were dated 1988 and so being 6 years after the fateful day, I thought I would be just wasting my time. When I got to the second to last photo, I came across an object that looked way out of character to everything else in any of the photos:
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