View Full Version : Vsv Actuator Fault
Dear all 737-800 Engineers
Please help after each engine start fuel starts leaking from the engine drains, After inspection from engineers it was traced from VSV actuator as it cures it self after attempting another engine start however the fault is still registered in the FMC as "VSV ACTUATOR SIGNAL OUT OF RANGE" in all flt legs.
Lightning5
1st Nov 2008, 12:35
Check FIM. Could be a VSV act. feedback cable defect.
Lightning5
1st Nov 2008, 18:27
just to clarify my previous input. The EEC is looking at the range of movement of each actuator (normally in %) and compares it to its own valid range in memory. If the range is different, or the EEC cannot determine the range the message is punched up. The EEC also compares both A and B channel inputs and operates on the input that is valid. With such an important engine system (VSV/VBV) I am suprised that an ENGINE CONTROL message has not appeared although it has been some time since I looked at the fault regime. maybe the harness needs tweeking:)
IFixPlanes
1st Nov 2008, 20:00
My opinion is that the leak has nothing to do with the fault message.
BTW: These kind of faults are stored in the EEC mot the FMC.
The fault is stored in the EEC memory, So do you suspect that this leak is coming from the HMU somewere.
The engneers C/Out actuator test through the FMC Maintenance engine page however it was NIL faults.
IFixPlanes
4th Nov 2008, 07:13
The fault is stored in the EEC memory, So do you suspect that this leak is coming from the HMU somewere.
No, the leak could be on the VSV actuator.
A slightly misaligned seal in the VSV actuator can couse a leak out of the drain port.
By performing a actuator test or starting the engine the seals realign most of the time.
http://img396.imageshack.us/img396/3256/b737ngvsvactuatorpb3.th.jpg (http://img396.imageshack.us/my.php?image=b737ngvsvactuatorpb3.jpg)
The message "... SIGNAL OUT OF RANGE" normally indicates that the EEC detects a signal which is not in the valid range.
This has nothing to do with a leak.
More important than the message is the fault number. It is shorter, gives you more information and the chance of misspelling is lower.
The message "VSV ACTUATOR SIGNAL OUT OF RANGE" does not exist! :zzz: