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Horror Stories

ZA40 Mishaps

 

 

Mishap Number 1: Pump Drive Dropped Off

 

The ZA40 can be fitted with engine driven pumps.

 

In this first breakdown The pump drivewheel fitted on the front end of the engine became detached whist the engine was running, damaging the engine casing. The engine was relatively new and and had only run a few thousand hours. The first the watchkeepers knew about it was when the engine shut down on Low LO pressure. As can be seen from the photos, the bolts holding the wheel in place had become unscrewed and had become badly bent. Leads to suspicion of incorrectly torqued bolts and locking wire of incorrect specification, incorrectly fitted.

 

End Cover and Drive Gear Removed from Engine

End of Engine Showing Vibration Damper and  Fixing Flange for

Drive Gear

Fixing Bolts and Pieces of Locking Wire Retrieved from Engine Casing

Gear Drive on Pump Showing Damage to Teeth

 

 

Mishap Number 2: Cracked Inlet Valves

 

The next sequence of photographs show the damage caused when an inlet valve cracked and broke. Pieces of the valve hammered around in the combustion space damaging head, liner and piston crown before wrecking the turbocharger.

 

The Final photograph shows how repeat of the failure was avoided during maintenance: As part of the maintenance routine introduced, the valves were crack detected during unit overhaul. This example was found to be cracked and given a sharp tap with a hammer.

 

Damaged Head and Valves

 

Close Up of Damaged Valve

 

Damaged Piston Crown

 

Damaged Turbocharger Blading

 

 

Inlet Valve Broken Across Crack

 

 

Mishap Number 3: Failed Bottom Ends

 

Overloading due to incorrectly timed fuel injection led to failure of two bottom ends. Some of the white metal from the bearing found its way to the spherical top end bearing and damaged that. A major repair involving crankshaft machining and regrind was required.

 

 

One of the Damaged Crankpins

 

 

Wiped Bearing Shells

 

Back of Bearing Shells Showing Overheating

 

 

White Metal Debris

 

 

Damage at Piston Top End

 

Re-Machining Crankpin

 

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