prop/mix adjustment

[higgybaby]

BE-76 POH says prop/mix "FULL FORWARD BELOW 100 KNOTS" for a slow flight.
what if i start with first mix..full reach /prop 2500 then decrease the speed?? could anyone answer??

Don't know much about the BE-76 aircraft, but here's some general guidelines for adjusting the prop.

When you want to add power (full power for example), make sure the prop is in the full increase (lowest blade angle) before adjusting power. On the other end when decreasing power, adjust the prop after decreasing the power setting.

In slow flight, you are generally in a landing configuration. As such, you are preparing the aircraft for the addition of power. In that case, you want the mixture and prop adjusted appropriately. In my Turbo Arrow, that's mixture full rich and prop full forward.

[djschaut]

This question depends on your altitude and how much time you have to bleed off your speed to below 100kts, as well as the altitude of the runway. If you're at 12,000' where the air is thinner, you don't want to go full rich on the mixture in that thin air--it can foul your plugs and valves. Also, if you push the prop full forward then, it will be harder to bleed off your speed. The best bet is to slowly bleed off your speed with the throttle while adjusting the mixture to your target EGT or TIT and do the other things to slow your speed--flaps, gear, whatever. Then, as you slow to your approach speed, which is likely 90kts, you go through your gumps check (Gas Undercarriage Mixture Prop Safety) prior to landing. You should have the prop forward and the mixture adjusted in the pattern. If you are landing in Leadville, Colorado, you probably don't want your mixture full forward until final if you're circling in the pattern--that field is at 10,000'. If you're at sea level, though, full mixture would be alright. There are conditions during which it is appropriate to push the propeller forward at a very high altitude--particularly the 'critical altitude' of the airplane. That's the altitude in a turbocharged airplane where it is starving for air and the prop is used to force more air into the cowling to maintain manifold pressure. Still, the mixture is guided by the TIT or EGT. Also, get into a routine of doing the same thing for each landing for that particular plane--so that when you're in trouble, you don't have to think about it--such as in bad weather or dark rain looking for the runway lights.

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DJSchaut

[sharplab]

This is the proper way. Lean mixture any time under 75% power or over 3000msl. Continue to lean until you are at cruise flight level and leave the mixture there. This will keep your engine warmer for your descents. If you engine is too lean then it will let you know. Being a little lean of peak egt is fine. Also for your descent set prop and power to 20/20. This prop setting will help keep a load on the engine thus keep it warm. After descent then 20/23 is fine and leave the prop there until short final. Vref usually works at around 14-18 inches man pressure. Remember after flying at 10,000 feet the fuel in your tanks has cooled and richening the mixture could have serious shock cooling effects. Hope this helps.
Stephen C. Sharp