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On December 21, 2009, at 1304 eastern standard time, a Czech Aircraft Works Sportcruiser special light sport airplane, N524SC, operated by Tidewater Flight Center, was substantially damaged during collision with trees and terrain following an inadvertent spin and dive recovery near Suffolk, Virginia. The certificated private pilot sustained minor injuries, and the certificated flight instructor was seriously injured. Visual meteorological conditions prevailed for the local instructional flight that originated at Chesapeake Regional Airport (CPK), at 1245, and was conducted under the provisions of 14 Code of Federal Regulations Part 91.
In both a telephone interview and a written statement, the pilot stated that he was recently issued his private pilot certificate and that the purpose of the flight was to be “checked out” in the Sportcruiser airplane. After departure, he flew the airplane a short distance to the training area to perform basic flight maneuvers. While flying about 2,500 feet mean seal level (msl); the pilot initiated a power-off stall. At the onset of the stall, he added power, the airplane “yawed left,” he applied right rudder and the airplane “snapped into a tight spin to the left.”
According to the instructor, the pilot was performing slow-flight maneuvers, and because the airplane was already configured, she suggested he perform a power-off stall. She said, "He reduced power to idle, and as the airspeed decreased, he increased the pitch attitude to induce a stall. We were climbing through to about 2500 feet MSL at this point. The aircraft then started veering to the left. He attempted to correct, but before he could do so with enough rudder the Sport Cruiser rolled into a spin."
The instructor announced that she had the flight controls, and the pilot released the controls. The instructor verbalized her spin recovery control inputs as she performed them, but the airplane continued to spin and lose altitude. The airplane eventually stopped spinning, and during the post-spin dive recovery, the airplane struck trees and terrain, and came to rest inverted.
The flight instructor was interviewed by telephone and her statement was consistent with the pilot’s. Both she and the pilot stated that it was a “surprise” how quickly the airplane rolled into the spin after the stall. Each of them also described the handling characteristics of the airplane as “touchy” and “sensitive” to control inputs, but during slow flight the controls were “mushy.”
A review of Federal Aviation Administration (FAA) airman records revealed that the pilot held a private pilot certificate with a rating for airplane single-engine land. His most recent FAA second class medical certificate was issued February 26, 2008. The pilot reported 99 total hours of flight experience with no prior experience in the accident airplane make and model.
A review of FAA airman records revealed that the flight instructor held a commercial pilot certificate with a rating for airplane single-engine land and instrument airplane. She also held a flight instructor certificate with a rating for airplane single-engine land and instrument airplane. Her most recent FAA second class medical certificate was issued July 11, 2008. The flight instructor reported 470 total hours of flight experience with 20 total hours of experience in the accident airplane make and model.
According to FAA and maintenance records, the airplane was manufactured in 2007 and had accrued 868 total aircraft hours. Its most recent conditional inspection was completed on November 17, 2009, at 826 total aircraft hours.
As of April 4, 2009, Czech Sport Aircraft owned the design rights for the SportCruiser and provided airworthiness support for all of the SportCruisers that were built by Czech Aircraft Works and subsequently by Czech Sport Aircraft.
On January 19, 2010, the SportCruiser was renamed the PiperSport and was distributed worldwide by PiperSport Distribution Inc.
On January 13, 2011, Piper Aircraft Inc. terminated its licensing agreement and the Sportcruiser was then distributed worldwide by Czech Sport Aircraft.
At 1944, the weather reported at TLH included clear skies and calm wind. The visibility was 10 miles. The temperature was 15 degrees C and the dew point was 12 degrees C. The altimeter setting was 30.23 inches of mercury.
At 1300, the weather reported at CPK, 10 miles east of the site, included scattered clouds at 4,900 feet and wind from 280 degrees at 6 knots. The visibility was 10 miles. The temperature was 7 degrees C and the dew point was -4 degrees C. The altimeter setting was 30.09 inches of mercury.
Examination of the airplane at the scene by an FAA inspector revealed substantial damage to the engine compartment, and partial separation of the wings. The airplane was recovered from the site on December 29, 2009, and examination during recovery revealed no pre-impact mechanical anomalies.
The accident airplane was involved in a previous accident on December 23, 2008 (NTSB ID ERA09LA111). The investigation compared the actual, published, and placarded (on the airspeed indicator) v-speeds for the airplane, and none matched. Further, the investigation determined that the calibrated-to-indicated airspeed chart published in the Pilot Operating Handbook (POH) was inaccurate.
As a result of the investigation, the pitot-static system on the SportCruiser was modified by inclusion of an AVIATIK WA037383 pitot-static probe in place of the previous design. The airspeed data was recomputed following flight tests that established calibrated airspeed (CAS), and compared it to the indicated airspeed (IAS) in the airplane. The POH was republished with the airspeed data derived from the flight tests and added a caution that "Airspeeds values are valid for standard AVIATIK WA037383 pitot-static probe."
The airplane experienced its second accident and was returned to service prior to the publication of the factual report for ERA09LA111, and the subsequent changes to the POH. Therefore, at the time of the second accident, the following information excerpted from ERA09LA111 still applied to the accident airplane:
The installed airspeed indicator's markings (miles per hour on the outside arc and knots on the inside arc) and airspeed color code range markings were different, from the airspeed indicator markings (knots only) and airspeed color code range markings shown on the airplane manufacturer's website for their "Standard 6-PAK" installation.
Further examination of the photographs also revealed that the installed airspeed indicator color code markings did not agree with the information published in the supplied airplane manufacturer's POH (Revision 1.0) which was published in March of 2006. Moreover, it was also discovered that not only did the color code range markings on the accident airplane not agree with the manufacturer's POH but also that the markings were inaccurate.
1. The bottom of the white arc (stall speed with flaps extended) was approximately 5 knots higher than published.
2. The top of the white arc (maximum flaps extended speed) was 10 knots lower than published.
3. The bottom of the green arc (stalling speed with flaps retracted) was approximately 3 knots higher than published.
ASTM Standards and the POH
Review of ASTM International's Standard Specification for Design and Performance of a Light Sport Airplane (ASTM Designation: F 2245-07), also revealed that "All flight speeds" were to be "presented" as "calibrated airspeeds."
Review of the supplied POH revealed however, that this was not the case, and that the airspeed limitations, and airspeed indicator markings published in the supplied POH, were actually presented as indicated airspeeds.
Furthermore, it was discovered that the stall speed information and airspeed indicator calibration information published in the POH in many cases contained large differences (in a couple of instances almost 20 knots) between the published indicated airspeeds and the published calibrated airspeeds.
Previous Special Light Sport Aircraft (SLSA) Airspeed Problems
This was not the first time that Safety Board investigators found Airspeed inconsistencies in SLSA airplanes and documents. Airspeed indicator, airspeed correlation, and POH inconsistencies were also discovered during investigations of a series of in-flight structural breakups of Zodiac CH-601XL airplanes that occurred in the United States between February of 2006 and March of 2009. During those investigations the Safety Board concluded that errors in airspeed correlation data would result in incorrect airspeed data in the pilot operating handbook (POH) and could result in a pilot inadvertently flying at unsafe airspeeds.
As a result of the investigation into the in-flight structural breakups, on April 14, 2009, the Safety Board issued recommendations to the FAA to:
"Determine the correct airspeed correlation between calibrated airspeed and indicated airspeed for the Zodiac CH-601XL, require that the correct data be included in existing and new airplane pilot operating handbooks (POHs), and ensure that the information on the airspeed indicator is accurate and consistent with the POHs. (Safety Recommendation A-09-36)."
"Work with ASTM International to incorporate additional requirements into the standards for light sport airplanes that provide for the accurate determination of airspeed data and for the adequate presentation of that data in existing and new airplane pilot operating handbooks and on airspeed indicators. (Safety Recommendation A-09-37)."
According to FAA Advisory Circular AC-61-23C, Pilot’s Handbook of Aeronautical Knowledge:
“The effect of torque increases in direct proportion to engine power, airspeed, and airplane attitude. If the power setting is high, the airspeed slow, and the angle of attack high, the effect of torque is greater. During takeoffs and climbs, when the effect of torque is most pronounced, the pilot must apply sufficient right rudder pressure to counteract the left-turning tendency...”
According to the FAA Airplane Flying Handbook, guidance for recovery from power-off stalls included, "Recovering from the stall should be accomplished by reducing the angle of attack, releasing back-elevator pressure, and advancing the throttle to maximum allowable power. Right rudder pressure is necessary to overcome the engine torque effects as power is advanced and the nose is being lowered. The nose should be lowered as necessary to regain flying speed and returned to straight-and-level flight attitude."
According to FAA Advisory Circular AC 61-67C, Stall and Spin Awareness Training:
107. SPINS. A spin in a small airplane or glider is a controlled (recoverable) or uncontrolled (possibly unrecoverable) maneuver in which the airplane or glider descends in a helical path while flying at an AOA greater than the critical AOA. Spins result from aggravated stalls in either a slip or a skid.
109. PRIMARY CAUSE. The primary cause of an inadvertent spin is exceeding the critical AOA while applying excessive or insufficient rudder and, to a lesser extent, aileron. Insufficient or excessive control inputs to correct for Power Factor (PF), or asymmetric propeller loading, could aggravate the precipitation of a spin. At a high AOA the downward moving blade, which is normally on the right side of the propeller arc, has a higher AOA and therefore higher thrust than the upward moving blade on the left. This results in a tendency for the airplane to yaw around the vertical axis to the left. If insufficient or excessive rudder correction is applied to counteract PF, uncoordinated flight may result. A classic situation where PF could play an important role in a stall/spin accident is during a go-around or short field takeoff where the airplane is at a high pitch attitude, high power setting, and low airspeed.