Learjet 35A Engine Failure and Uncontained Engine Part Release in Rendsburg

Incident Overview and Flight Details On 16 January 2023, a Learjet 35A operated by a German air transport company experienced a serious in-flight incident near Rendsburg, Germany. The aircraft, a twin-engine low-wing jet with serial number 35-331 and a 1980 build year, was conducting a target representation flight. The flight originated from Hohn Airfield (ETNH), a military airfield located north of Rendsburg in Schleswig-Holstein. The aircraft departed at 13:34 local time after an initial attempt was aborted due to a defective artificial horizon instrument. ## Engine Failure and Crew Response Approximately two minutes after takeoff, at an altitude of around 7,000 feet AMSL, the aircraft experienced a severe vibration and a loss of thrust on the left engine. The low-pressure compressor (N1) indication dropped to 0, while the high-pressure compressor (N2) fell to 11%. The co-pilot announced the loss of the left engine. The captain, who was the pilot flying, aborted the climb, declared an emergency, and set the left engine to idle before shutting it down. The crew performed the applicable memory items and, due to the unassessable extent of the damage, elected to return to Hohn for a visual approach. ## Damage Assessment and Landing The aircraft landed on runway 08 at Hohn after a six-minute flight, with a landing weight of 16,800 lbs, which exceeded the maximum landing weight of 16,000 lbs. Post-landing inspections revealed that the left engine cowling was partially torn open. The combustion plenum flange to interstage transition duct was ruptured, with only 29 of 144 bolts remaining. The rotor assemblies of the first and second stages of the low-pressure turbine, along with the second-stage stator, were missing from the engine casing. Debris from the engine penetrated the left fuselage, creating impact holes and scratches above the pylon in the area of frames 25A and 26. Frame 25A was damaged, and additional minor damage, including dents and paint removal, was found on the left fuselage, tail, and horizontal stabilizer. An impact hole was also found on the right side of the left tip tank. No damage was reported to the primary or secondary flight controls, integral tanks, pressurized cabin, or wiring harnesses. ## Aircraft and Engine Specifications The aircraft was powered by two Honeywell TFE 731-2C-2B turbofan engines. The left engine, serial number P099295, had 7,373 hours and 4,949 cycles of operation, while the right engine, serial number P74485C, had 10,712 hours and 6,549 cycles. The aircraft had a total flight time of 22,658 hours. The left engine was equipped with a digital electronic engine control (N1 DEEC) system. Prior to the incident, oil samples from the left engine taken on 4 July 2022, 18 October 2022, and 17 January 2023 showed traces of metal wear and non-metallic solids, which were classified as normal by the laboratory. Engine condition trend monitoring for both takeoff and cruise parameters was also rated as normal. ## Crew and Operational Context The flight crew consisted of a 59-year-old captain holding an ATPL(A) license with 12,819 total flight hours and 7,510 type-rated hours, and a 49-year-old co-pilot holding a CPL(A) license with 3,510 total flight hours and 649 type-rated hours. Both held valid Class 1 medical certificates. The aircraft was certified for traffic in Germany, and its airworthiness certificate was valid until 29 August 2023. The operator's maintenance program, issued on 21 September 2022, had no hold items recorded. The incident resulted in no injuries, no third-party damage, and severe damage to the aircraft.