Chris Johnson, Index.
Formal Proof Techniques
- We know fan blades were CFM56s...
- Can we prove 2nd order vibrations occured?
A ground test engine was fitted with a set of
fan blades, some of which were fitted with
strain guages. This fan blade set was
selected so that all the blades had the same
natural frequency of their second order bending
mode. This test showed that, under these
conditions, there was an excitation of a non-
synchronous vibratort response but it did not
produce vibratory stress levels greater than
50 of the endurance limit.
(Page 58 from UK Air Accident Investigation Branch
report on the accident to Boeing 737-400 G-OBME near
Kegworth, Leicestershire on January 8th 1989.
- Worrying - ruins report's hypothesis...