Incident Description
On September 11, 2011, during a routine parts inspection at the operator's warehouse, it was discovered that pyrocartridges (Cartridge assy, PN 472001-01) installed in the engine fire extinguishers were accompanied by an EASA Form 1 certificate issued in 2007 that stated an incorrect service life. The cartridges were manufactured in April 1997 and had a manufacturer-specified service life of 10 years, which could not be extended. As a result, the components should have been retired in 2007.
Following the discovery, the operator ordered the removal of the affected cartridges from the serviceable parts inventory and instructed a check of components installed on the aircraft currently under maintenance. The check revealed that the pyrocartridges on the right engine should have been removed in 2007.
The operator, in coordination with the maintenance organization, found records of a functional test performed on July 31, 2007, in accordance with CMM 26-21-34. According to the CMM, this test is only permissible when a malfunction is suspected and cannot be used to extend the component's service life. In this case, the test was used to extend the life, which was non-compliant.
Investigation Findings
After the irregularity was identified, the operator ordered an inspection of pyrocartridges across its entire fleet and warehouse stock. The inspection found six cartridges with exceeded service life, including one aircraft where all four cartridges were expired. All affected components were replaced.
Cause and Contributing Factors
The cause of the incident was extending the service life of the component contrary to the manufacturer's documentation. Circumstances that influenced the incident included:
- The operator and the maintenance organization used the same computer system to monitor component service life.
- The possibility to extend the service life of similar components under the maintenance organization's Part 145 approval by performing tests.
Preventive Actions
The operator ordered inspection and replacement of the affected components. The maintenance organization informed its technical and warehouse personnel about the incident. The event was incorporated into human factors training during the maintenance organization's periodic training sessions.