What happened
On February 13, 2020, a Boeing 737-800-86J, registration SP-ENW, was preparing for a passenger flight from Marrakech Menara (GMMX) to Milan Malpensa (LIMC). During the pushback process from the parking stand, the crew attempted to start the number 2 (right) engine. During this initial attempt, the crew noted the absence of the required "START VALVE OPEN" indication and a lack of N2 rotation.
Following standard procedures for an aborted engine start, the crew completed the pushback from the stand and subsequently made a second attempt to start the right engine. While the "START VALVE OPEN" indication was present during this second attempt, the engine N2 rotation only reached approximately 9%. Consequently, the crew aborted the start sequence again and decided to return the aircraft to the parking stand.
The investigation
The investigation focused on the mechanical failure during the engine start sequence. Technical personnel were called to the aircraft to assess the situation. The maintenance crew determined that the aircraft could be released for flight under the Acceptable Deferred Defect (ADD) procedure, in accordance with MEL 80.1.2. The aircraft completed a subsequent flight the following day, after which the faulty component was replaced.
Findings
- The primary cause of the incident was a malfunction of the number 2 engine start valve.