On July 27, 2019, about 0535 mountain daylight time, a Swearingen SA227 airplane, N681TR, was substantially damaged when the left main landing gear collapsed during landing at the El Paso International Airport (ELP), El Paso, Texas. The captain, first officer, and observer were not injured. The airplane was registered to Sierra West Airlines, Inc. and operated by Pak West Airline dba Sierra West Airlines as a Title 14 Code of Federal Regulations Part 91 instructional flight. Visual meteorological conditions prevailed, and the flight was not operated on a flight plan. The local flight originated from ELP about 0430. The captain noted the purpose of the flight was second-in-command pilot training for the first officer and the observer in turn. He reported that after takeoff the landing gear retracted normally. They executed a practice instrument approach to a missed approach. When attempting to retract that landing gear after initiating the missed approach, the left main gear in-transit light remained illuminated. The right main and nose landing gears retracted normally. Both hydraulic system low pressure warning lights subsequently illuminated. Efforts to troubleshoot the problem using the emergency checklist and extend the landing gear manually were not successful. The captain ultimately landed with the left main landing gear partially extended. The subsequent loss of directional control resulted in a runway excursion and an impact with an airport sign. A postaccident examination revealed damage to the outboard left wing, left main landing gear and left propeller. Some hydraulic fluid was present in the left main landing gear wheel well and no hydraulic fluid was observed in the reservoir sight gauge or on the dip stick. The base manager for the airline reported that the left main landing gear drag brace failed consistent with the accident. The actuator and brace were replaced to allow the airplane to "stand" on the left main landing gear. Hydraulic pressure was subsequently applied to the airplane, and no leaks were observed in the landing gear system. A leak was observed in the hydraulic line to the left flap; however, that also appeared to have been a result of the accident. Airplane maintenance records indicated that hydraulic fluid leaks in the left main landing gear wheel well were noted on June 25th and again on 26th; about 30 days before the accident flight. These were repaired and the airplane was returned to service. On June 30th, the hydraulic fluid level was low and was replenished. About 30 hours flight time elapsed between that maintenance action and the accident.