Rotec AEROSPORT R2800, Operation Manual, Page: 62 / 87

62 | ROTEC AEROSPORT
www.RotecAerosport.com
ENGINE OPERATING
PROCEDURE
Hydraulic lock on radial engines occurs most commonly post flight. After shutdown, hot oil weeps past the piston
rings and fills the combustion chamber(s) and or intake pipes with oil. If this accumulation of oil is not removed from
the combustion camber(s) prior to the next start then as the piston approaches TDC (top dead centre) it will attempt
to compress the accumulated oil. As oil is a liquid and liquids cannot be compressed, any further attempt to complete
the cycle results in redistributing the immense forces back through the connecting rod causing it to buckle and or
bend.
A bent rod would prevent the piston’s movement up and down the bore in a straight line; consequently the piston
would be cocked over and rubbing on the cylinders side walls resulting in an increased friction and wear.
Typical symptoms:
• Smokey Cylinder(s)
• Loss of Power
• Excessive Heat on the Cylinder
• Roughness in Idle
• Roughness in Running
• Loss of compression on the cylinder in question (the lowering in the compression is attributed to a shortened pis-
ton deck height resultant from the bend in the rod)
• Fowling of the spark plug (when compared against other plugs)
Further flight should cease if you experience one or more of these symptoms until the cause can be accounted for.
If the deformation is slight, the engine may start and run seemingly without problem. In general, providing all remain-
ing cylinders function correctly, there is sufficient power generated for flight.
The real danger of not detecting a bent rod occurs when the distorted or bent rod snaps through the continuous flex -
ing caused by the misalignment of the piston with the bore and the reciprocating action of the engine. Once the rod
snaps, the engine’s main power station suffers further internal damage. If this happens in flight, immediate emergency
landing is required.
WARNING
Once the connecting rod is bent, it cannot be straightened and it must be replaced. To replace a damaged connecting
rod, a full engine overhaul is required.
NOTE
If you believe you have suffered Hydraulic Lock, contact Rotec Aerosport to seek technical advice and or rectification
strategies.
NOTE
Rotec Aerosport requires strict adherence to the pre-flight and post-flight procedures contained within this manual to
avoid the phenomenon known as “Hydraulic Lock”. It is easy to damage an engine if these measures are not followed.
Any engine damage sustained by Hydraulic lock is not covered by warranty as it is easily avoided by following theses
operational guidelines.
WARNING: HYDRAULIC LOCK
HYDRAULIC LOCK SYMPTOMS
FLYING WITH A BENT ROD