Section 4 – Normal procedures
Checklists
Page 4 - 22
5.8. CRUISE
1. Power: set performance as required, refer to table in section 5 of AFM
2. Fuel tank selector: as required to maintain symmetric balance
3. Mixture: set in accordance with following para 5.9
To optimize engine life, the cylinder head temperature (CHT) should lie
between 150°F and 400°F in continuous operation, and not rise above
435°F in fast cruise.
Monitor and manually compensate asymmetrical fuel consumption by
switching fuel selector valve. Switch ON the electric fuel pump prior to
swap the fuel feeding from one tank to another.
5.9. MIXTURE ADJUSTMENT RECOMMENDATION
The maximum permissible cylinder head temperature (500 °F) must never be ex-
ceeded.
The mixture control lever should always be moved slowly.
Before selecting a higher power setting the mixture control lever should, on each
occasion, be moved slowly to fully RICH before throttle adjustment.
Care should always be taken that the cylinders do not cool down too quickly.
The cooling rate should not exceed 50 °F per minute.
For maximum service life cylinder head temperature should be kept below 475 °F
(high performance cruise) and below 435 °F (for economy cruise).
Best Cruise Economy Mixture
The best economy mixture setting may only be used up to a power setting of 75 %. In order to obtain
the lowest specific fuel consumption at a particular power setting, proceed as follows:
- Slowly pull the mixture control lever back towards LEAN until the engine starts to run rough-
ly.
- Then push the mixture control lever forward just far enough to restore smooth running. At the
same time the exhaust gas temperature (EGT) should reach a maximum.
Best Cruise Power Mixture
The mixture can be set for maximum performance at all power settings:
- The mixture should first be set as for best economy.
- The mixture should then be enriched until the exhaust gas temperature is approximately
100°F lower.
This mixture setting produces the maximum performance for a given manifold pressure
and is mainly used for high power settings (approximately 75 %).
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