Warbird Information Exchange

A report on tonight's 10 P.M. news here in the Seattle area says Boeing has issued a service bulletin concerning a brief uncontrolled engine acceleration during climb out. 32 instances have been reported over the last 5 years where one or both CFM-56 engines on 737 next gen aircraft have had an up to 10 second acceleration during climb out. The engine surges to a higher power setting and returns to it's previous settings uncommanded.
The FADEC was upgraded in December fleet wide and no instances have been reported since, Boeing and carriers are looking @ things such as delivery and handling of JET 'A' and changing fuel controls after an incident, the VSV (variable stator vanes in the 4th to 10 stages of the low pressure compressor)control is also being looked into since it operates in conjunction with the thrust levers/fuel control.
So far, nothing coming from the FAA.

I'm not sure that fuel quality has that much to do with it unless the screens aren't catching something that is causing the flowmeters to not read properly. The fuel system in the 737's is extremely robust and simple and the only real change between the Classic and NG tank systems are the length of the supply lines from the fuel tanks. I suspect it may be similar to the CFM issue that reared its head in the A32X series years ago and that it was a software issue more than anything.

CAPFlyer wrote:I'm not sure that fuel quality has that much to do with it unless the screens aren't catching something that is causing the flowmeters to not read properly. The fuel system in the 737's is extremely robust and simple and the only real change between the Classic and NG tank systems are the length of the supply lines from the fuel tanks. I suspect it may be similar to the CFM issue that reared its head in the A32X series years ago and that it was a software issue more than anything.

I would tend to agree, but I'm sure Boeing is like the AFLAC duck in the row boat, busy trying to cover every possible hole in the bottom given the issues still unsolved concerning the batteries in the 87. My opinion is 32 incidents divided by 5 years based on 16000 ops fleet wide per day makes odds pretty slim, but ALASKA AIR claims 16 of those incidents and 14 by 'another carrier' HMMMM-