Based on preliminary findings from the investigation of a partial gear up landing of a CRJ200 in December 2008, as well as prior investigative findings, the U.S. NTSB voiced its concerns about training for mechanics and inspectors. Two safety recommendations were issued and three older recommendations were re-iterated.
On December 14, 2008, about 17:00 local time, Air Wisconsin Airlines flight 3919, a Canadair CL-600-2B19 (CRJ-200), N407AW, landed at Philadelphia International Airport, PA (PHL), with the left main landing gear in the retracted position. The aircraft was being flown as a repositioning flight from Norfolk International Airport, VA (ORF) to PHL. There were no injuries to the two flight crew and one flight attendant on board the aircraft.
The flight crew received indications of a left main landing gear problem prior to landing and stated that they completed the applicable Quick Reference Handbook (QRH) procedures, but were unable to lower the left main landing gear. They elected to land with the nose and right main landing gear in the down and locked position and the left main landing gear up.
Maintenance had been performed on both the left and right main landing gear systems prior to the incident flight. Post-incident inspection of the aircraft revealed that, the upper attachment bolt for the left main landing gear uplock assembly, which is designed to be attached to both the uplock mechanism and the structure, was attached to the airplane structure only.
The NTSB concludes that the incident mechanic was not properly trained or supervised when he replaced the uplock assembly on the incident airplane for the first time, which led to the error in installation. Further, the error was not detected by the inspector. The NTSB is concerned that the Federal Aviation Administration (FAA) does not currently require mechanics to receive on-the-job training (OJT) or be supervised while performing required inspection item (RII) tasks for the first time.
Problems with untrained or unsupervised mechanics performing maintenance tasks for the first time have also been found during the NTSB’s investigation of the January 8, 2003, fatal accident involving a Beechctaft 1900D which crashed shortly after takeoff at Charlotte-Douglas International Airport, NC. The accident airplane underwent a detail six maintenance check. One of the mechanics assigned to check the elevator control cable tension was receiving OJT under the supervision of a quality assurance inspector who failed to adequately supervise and direct the mechanic.
Therefore, the NTSB recommends that the FAA:
Require that mechanics performing required inspection item and other critical tasks receive on-the-job training or supervision when completing the maintenance task until the mechanic demonstrates proficiency in the task. (A-10-96)
Require that required inspection item (RII) inspectors receive supervision or on-the-job training on the proper inspection of RII items until the inspector demonstrates proficiency in inspection. (A-10-97)