Flight Testing Maneuvers
The mishap airplane, with the pilot flying from the left seat, rendezvoused with another Learjet to begin a series of profiles for flight testing. The crew noted that the horizon was very difficult to discern. While maneuvering for the second set of data points, the pilot lost sight of the other airplane. To remain clear, the pilot rolled right. However, glare from the sun impaired his vision, delaying his recognition that the airplane was entering an unusual attitude.
Unusual Attitude and Recovery
By the time the pilot initiated recovery, the airplane was in an estimated 70-degree right bank and 50-degree nose-down attitude, with an airspeed of 380 KIAS. During the dive, the crew observed definite shuddering, but they did not experience any rolling tendencies or vibrations transmitted through the control yoke. The airplane sustained an in-flight loss of the right elevator during this upset.
Controllability Check and Landing
The crew conducted a controllability check by slowing the airplane to 150 KIAS and lowering the landing gear. At that condition, the airplane exhibited no unusual flight characteristics. The remainder of the flight and the landing were uneventful.
Post-Flight Discovery
During post-flight inspection, the aircrew discovered that the right elevator was missing. The loss occurred during the in-flight upset while maneuvering.