Palm Springs, CA, USA
N595DY
CZECH SPORTPLANES SRO DYNAMIC
The pilot was landing the light sport airplane at the termination of a 2 1/2-hour-long flight. During final approach, the airplane encountered a strong downdraft and the canopy extended to the full up position. The pilot was unable to reach the canopy handle to close it, and the airplane landed hard, likely due to the drag created by the open canopy. The left horizontal stabilizer and left aileron were substantially damaged. Postaccident examination revealed that the canopy latch did not always fully engage in the cabin frame during the closing operation; the latching pin would sometimes extend about 5 millimeters short of the 15 millimeters of full travel. Thus, it is likely that the pilot's encounter with a strong downdraft could have caused the canopy to flex and open if the latch was not fully engaged. In 2008, the airplane's manufacturer issued a Mandatory Service Bulletin requiring a revision to the flight manual. The revision stated that, if the canopy locking pin is not securely latched during the pre-flight inspection, the canopy could open in flight. The revision included operational updates specifying procedures for securing an inadvertent canopy opening during various phases of flight. The procedures stated that provided the airplane is flown in a straight and level attitude, the canopy will only partially extend, and could be retracted and locked by hand. The procedures warned that, during uncoordinated flight, the canopy will extend to the full open position, acting as an airbrake and resulting in an excessive descent.
On January 9, 2011, about 1535 Pacific standard time, a Czech Sportplanes SRO, Dynamic WT9 light sport airplane, N595DY, landed hard at Palm Springs International Airport, Palm Springs, California. The student pilot was operating the airplane under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. The pilot was not injured, and the airplane sustained substantial damage to the left horizontal stabilizer and left aileron. The cross-country personal flight departed Marana Regional Airport, Tucson, Arizona, about 1300. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported that during the final approach the airplane encountered a strong downdraft. As he attempted to recover control, the airplane's canopy opened, and extended to the full up position, such that he was unable to reach the handle to retract it. The airplane descended rapidly, and he applied full throttle in an effort to arrest the descent. As he approached the runway threshold he reduced engine power, the airplane descended rapidly, and landed hard. The airplane then departed the runway, coming to rest in the adjacent gravel verge. The composite airplane was equipped with a tip-up canopy, hinged at the forward cabin area, aft of the firewall. The canopy was locked in the down position by a single longitudinal spring-loaded latch pin, located in the center aft section of the canopy, above and behind the cabin seats. Lateral canopy support in the down position was provided by a set of two guide pins, which slide into slots in the aft cabin frame pillars. A set of gas struts were incorporated into the canopy frame to assist with raising the canopy. Examination of the airplane by the National Safety Board (NTSB) investigator-in-charge following the accident revealed that the latching pin, in the locked position, extended 15 millimeters beyond the canopy frame. During the examination, the latch was cycled in and out by hand, and it was found that the pin would intermittently extend 5 millimeters short of the full travel. The pilot stated that the latch was fully extended prior to departure. No damage was noted to the striker latch pin or guide pin striker plates. The airplane was not equipped with an audio or visual lock indicator. The airplane's manufacturer issued Mandatory Service Bulletin ZBTWT9 10A/2008 on October 23, 2008. The Service Bulletin addressed a series of operational updates, requiring a revision to the flight manual. The revision stated that the pin extends between 8 and 12 millimeters when locked, and if the pin is not securely latched during the pre-flight inspection, the canopy could open in flight. The revision included operational updates specifying procedures for securing an inadvertent canopy opening during various phases of flight. The procedures stated that provided the airplane is flown in a straight and level attitude, the canopy will only partially extend, and can be retracted and locked by hand. The update included the following warning: "During side-slipping flights with partial cockpit canopy latching (incorrect turn – slipping turn, skidding turn, and side slipping for landing) due to asymmetrical flow over fuselage by the air flow, the cockpit canopy will be carved through the gap and subsequently will be full open by help of the gas struts. The cockpit canopy will become the braking shield, what will cause abnormal airplane descent due to increased total drag."
Inadvertent opening of the airplane canopy during the landing approach in a downdraft, which resulted in a rapid descent and hard landing.
Source: NTSB Aviation Accident Database
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