ERA11FA133 · Potez-Air Fouga CM 170 MAGISTER

After the repair of a number of hydraulic leaks, a post-maintenance check flight was conducted from the vintage jet trainer's home airport with a visiting pilot/mechanic and the pilot/owner onboard. After the airplane took off, it departed the airport traffic pattern for in-flight tests. About 11 minutes later, the airplane reentered the airport traffic pattern and completed a left, overhead, mid-field break about 600 feet above ground level (agl). A voice recognized as the pilot/mechanic's then advised the tower that the three landing gear were down and locked, and the airplane arrived at the abeam position about 500 feet agl and 215 knots. The airplane then eased out of the turn and briefly flew a straight course that angled toward the runway before commencing a sharp turn toward the runway with an observed 90-degree angle of bank. The airplane was then seen descending rapidly before pitching up, overshooting the extended runway centerline, nosing down, and impacting the ground. Both pilots were ejected when the airplane impacted the ground, and neither of the destroyed cockpits nor an airport security video could provide definitive evidence as to which pilot was in which seat. However, because the pilot/mechanic’s voice was on all radio transmissions, including a transmission that he was unfamiliar with the airport, it is likely that he was in the front seat and flying the airplane.

Wreckage examination revealed that the airplane had impacted the ground in an approximately 45-degree left angle of bank, about 5 degrees nose-low. The landing gear were down and the push button selectors were in the "normal" position, indicating that landing gear were extended normally. The two left-wing flap segments were separated from the extensively damaged wing, and the differing cockpit wing flap indicators were unreliable due to cockpit and airplane damage. However, the two relatively intact right-wing flap segments were up and flush with the wing, consistent with the flaps being up at impact. The emergency airbrake selector was in the "out" position, indicating that the pilot/mechanic had recognized a loss of hydraulic pressure after lowering the landing gear, but before he could effectively deploy airbrakes or flaps. There are no means to lower flaps following a loss of hydraulic pressure. The pilot/mechanic should have extended the downwind leg for a flaps-up approach, per the abnormal procedures. However, he continued the high angle-of-bank, as-configured approach, but did not maintain sufficient airspeed to preclude an "accelerated maneuver stall."

Verbatim NTSB analysis and probable cause from the NTSB dataset