EASA SIB 2007-20
FAA SAIB NE-07-41 - Pratt & Whitney JT9D-7A and -7J Engines - Maintenance of the High Pressure Turbine (HPT) 2nd Stage Vane Assemblies
Summary
FAA Special Airworthiness Information Bulletin NE-07-41 is an informational bulletin addressing maintenance issues with Pratt & Whitney JT9D-7A and -7J series engines, specifically the high pressure turbine (HPT) 2nd stage vane assemblies. The bulletin highlights an engine separation event on a Boeing 747 caused by improper installation of the HPT 2nd stage vane assembly, which led to disk rim failure. It applies primarily to Boeing 747 aircraft equipped with these engines.
What Changed
This bulletin introduces awareness of improper maintenance practices related to the HPT 2nd stage vane assemblies that can cause engine failure. It provides recommendations for inspection and maintenance procedures but does not mandate regulatory changes or airworthiness directives. The FAA is monitoring the fleet but has not identified a broader unsafe condition requiring mandatory action.
Why It Matters
This information is critical for operators, maintenance organizations, and compliance teams to prevent uncontained engine failures and potential engine separations. Proper installation and torqueing of the HPT 2nd stage vane bolts are essential to avoid costly repairs and ensure flight safety. Awareness of this issue helps maintain engine reliability and airworthiness without immediate regulatory burden.
What To Do
Operators should review and ensure compliance with Pratt & Whitney or FAA-approved procedures for installing the HPT 2nd stage vane assemblies. Engines suspected of having improperly torqued vane bolts should be removed from service immediately. At the next maintenance opportunity, visual inspections of the HPT 2nd stage disk should be performed, and any disk showing circumferential scoring should be removed from service.
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