Learjet 35 crew reported the left engine lost power and began to roll back during climb out resulting in an air return.
Synopsis
Learjet 35 crew reported the left engine lost power and began to roll back during climb out resulting in an air return.
Narrative
Routine maintenance test flight to check new avionics installation. Pre-flight Fuel Computer check was fine. On climb-out; crew noticed flickering of left engine N1 but had to remain focused on following altitude; speed restrictions and talking to ATC while watching for traffic in busy ZZZ airspace. However; passing 2500 ft. in the climb to 3000 ft; the [L FUEL CMPTR] annunciator light illuminated and almost simultaneously the left engine N1 began rolling back until it just showed idle/windmilling indications. Second in Command (SIC) performed 'Engine Failure above V1' Immediate Action items; then PIC announced he had control of aircraft; himself then performing the same Immediate Action items. SIC contacted ATC to [request priority handling] and request immediate return to ZZZ1. Concern the other engine might fail as well (possibly due to fuel contamination); crew maintained 3000 ft. and turned left downwind for ZZZ1 Runway XX; planning to remain high and turn left base within gliding distance of the [fields]. Crew performed remainder of 'Engine Failure After V1' Emergency Checklist followed by 'Single Engine Landing' Abnormal Checklist. SIC tuned in ILS XX for glideslope information and we turned Final around 6 NM for Visual Approach to Runway XX. Once established on Final Approach; flap and landing gear deployment was delayed until crew was certain field could be made with no power should the other engine fail. Single-engine landing performed uneventfully. After landing; aircraft was inspected on taxiway 1 by Fire Department officials; after which crew taxied back to the ramp.
Second reporter narrative
On Day 0; I was called out on a routine test flight for Aircraft X. We first completed the walk around and fueled the plane for departure. We were cleared for takeoff on Runway XX. ATC advised us to climb to 2000 on a heading of 330. When reaching 1000 feet; we saw an anomaly in the left engine. ATC advised us to continue to climb to 5000 and upon reaching 3000 feet; we had a full rollback in the left engine. We decided at that moment that the best course of action was to exchange controls. I [requested priority handling] and requested a visual for Runway XX due to left engine failure. We completed the memory item for engine failure after V1 and single engine landing checklist. We decided to turn base to final and continue for a visual for Runway XX. Upon landing on Runway XX; we taxied off on 1 and met with the fire rescue team. After their check up; we continued taxing to our ramp.Suggestion: No engine failure.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.