Cracking Up - NTSB Reports

Prior to installing an overhauled fuel cell, it was found to contain a large quantity of sawdust-like particles. Further inspection revealed the foam filling the fuel reservoir was breaking down. The older cells reservoir foam insert was compatible with 100/130 fuel. However, 100LL causes the foam to break down into fine particles that get trapped in filters and screens. This problem is addressed in service bulletin (SB) number 2109 which replaces the old style foam (p/n 369200157) with a product that is suitable for use with 100LL.

Editorial Staff

Tuesday, May 20, 2008 at 12:00 AM ET

Verified

Key Takeaways:

Beech B55 Baron fuel cell foam, designed for 100/130 fuel, can disintegrate into particles when exposed to 100LL fuel, a problem addressed by Service Bulletin 2109.
Superior-brand cylinders on Continental IO-520-F engines have been reported with cracks originating at the exhaust valve seat.
Cessna 150/152 aircraft frequently experience cracks, breaks, or corrosion in the aft fin attach fittings (p/n 0431009), an issue technicians should remain aware of due to high-stress operational use.
A Continental IO-240-B17B engine experienced a jammed fuel pump mixture control shaft, leading to a lean mixture and requiring the fuel pump's replacement.