The engine of an A321 aircraft was being replaced. The maintenance team installed the engine bootstrap equipment that is used to hold and lower the engine during the removal task. When the engine was disconnected and separated from the pylon, the engine suddenly fell. Fortunately, nobody was injured. The engine pylon was damaged and needed to be partially replaced. The engine was damaged beyond economical repair.
Event Analysis
Rupture of a bootstrap attachment
Inspection of the bootstrap equipment on the hanging engine showed that one of its attachments had bent under the load of the engine and it eventually ruptured, which released the engine it was supporting, causing it to be damaged from the fall.
Unapproved bootstrap
The investigation found that the bootstrap equipment was not compliant with the Airbus technical specifications. The sizing and material of the attachments, which were a part of this equipment, were not correctly sized and this caused the equipment to fail.
The supplier of the engine bootstrap equipment was not listed in the Airbus Tools and Equipment Manual (TEM). The Operator had found the equipment supplier on the internet. The bootstrap equipment advertised on this supplier’s website indicated the same part number as the one listed in the AMM, but its cost was significantly lower than the equipment available from approved suppliers listed in the TEM.
Source – Airbus Safety Magazine