Pilot Debrief

ZENITH Zodiac CH601XL near Temecula, CA — 2021-11-23

Final reportWPR22FA048
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Date
2021-11-23
Location
Temecula, CA, USA
Airport
F70
Aircraft
ZENITH Zodiac CH601XL
Registration
N601KS
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Climb

Probable cause

The failure of the airplane’s canopy latch system, which resulted in the canopy opening in flight and a loss of airplane control. Contributing to the accident was the lack of a secondary canopy latch as recommended by the kit manufacturer.

Contributing factors

Contributing to the accident was the lack of a secondary canopy latch as recommended by the kit manufacturer.

NTSB narrative

About seven minutes after departure, following what appeared to be an uneventful takeoff and initial climb, the airplane began a 180° turn toward the departure airport. A few minutes later, witnesses heard a loud bang, and the airplane pitched down aggressively, rolled inverted, and impacted the ground in a steep, nose-down attitude. During the descent, the pilot’s flight bag and other cabin contents fell out of the airplane, and the sound of buffeting wind noise and the pilot struggling were heard on the airport’s common traffic advisory frequency. Examination did not reveal any anomalies with the flight controls or engine that would have precluded normal operation, and all components from the airplane were found in the immediate vicinity of the impact site. There was no evidence of bird strike. The owner/builder of the airplane stated that he had once experienced the canopy opening on takeoff but was able to land safely. As a result of this event, he disabled the standard lock and installed a set of two small over-center latches, each mounted to the rear sides of the canopy frame with two soft aluminum rivets. Examination of the canopy system revealed damage signatures that appeared to indicate that the rivets of one latch had separated in shear, and the other latch had twisted away from the airframe. It is likely that the accident was initiated by the failure of the mounting rivets in one latch, which caused the canopy to partially open on one side, then twist the latch away from the other side, resulting in an open and possibly deformed canopy. The reason for the initial failure could not be determined; however, the owner of the airplane was shorter than the pilot and had raised the seat and moved it forward during construction. The modification would have resulted in the accident pilot having to lean inboard, or sit with his head tilted, to avoid touching the canopy. It is possible that the airplane encountered turbulence that caused the pilot to hit the canopy, resulting in the failure of one of the latches. Multiple instances of canopies opening in flight were reported for this airplane model. Because an open canopy disturbs airflow over the horizontal stabilizer, flight control difficulties can result in a loss of control nose-down pitching motion, often accompanied by a loud banging sound and cabin contents being sucked out, all which were observed in this accident. Although the Pilot Operating Handbook (POH) provides instructions for continued flight with an open canopy, evidence from both this and previous accidents suggests that both the nose-down motion and associated negative G-forces can be hard for pilots to maintain airplane control. The airplane’s POH suggested the installation of a secondary backup latch system, and 2 weeks following the accident, the manufacturer issued a safety alert recommending such. The accident airplane was not equipped with a secondary latch.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot could have chosen to land immediately after canopy opened.

NTSB coding

Evidence available

  • 15 docket documents
View NTSB final reportView NTSB docket

Docket documents15

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