I recently experienced a reduction in power during takeoff and climb in my Warrior. On start I noticed the engine started right up without the need for priming, but idled a bit rough. The roughness disappeared during runup. During takeoff the climb was a struggle - a Vx climb gave only 250-300 fpm. At pattern altitude full power gave only ~2300 rpm and ~95 kias. I also noticed a 'hot' smell in the cabin - as if something was overheating.
Today I spoke to the planes owner who stated that there was a 'primer malfunction' - the mechanics are guessing the primer knob was not locked on takeoff, which could account for the poor performance. Further investigation suggests that this might be a viable explanation for my situation.
I did a bit of research since my original post and located an FAA Advisory Circular that discusses the primer issue: AC No: 20-105B Subject: RECIPROCATING ENGINE POWER LOSS ACCIDENT PREVENTION
AND TREND MONITORING. A quote from the maintenance section of this document states:
'Engine Primer. The primer is a simple system in which raw fuel is drawn from the engine supply line and injected into two or more of the engines cylinders by means of a small hand operated pump. If the primer pump handle is not locked in the closed position, raw fuel will continue to be drawn into the cylinders by the suction created in the affected cylinders during the intake cycle. The engine will run rough at low RPM, mimicking magneto problems,
but will smooth out above 1700 RPM. The exhaust at low RPM will be black and smoky, and the fuel/air mixture will be extremely rich in the affected cylinders. Leaning the engine manually may restore smoother operation but excessive leaning will raise the cylinder head temperature in the cylinders not equipped with engine primer lines. A similar operating condition may exist if the 0 rings in the primer pump are nicked or cracked which allows fuel to pass the 0 rings and into the cylinder even if the pump handle is stowed and locked. If this condition is suspected have a certificated mechanic check the primer system.'
This sounds very much like the situation I experienced in the Warrior.
Further investigation of the Sensenich 74DM6-0-60 prop, which is installed on the Warrior, revealed the max throttle 'static' RPM should be between 2350-2450. The Warrior POH supports this info.
Additionally Lycoming engine documentation indicates that every model of the O-320 series 160 HP engine that they manufacture has a rated takeoff rpm of 2700.
I'll be sure and keep an eye on static and dynamic RPM during my next flight.
Thanks again to all who replied.
Today I spoke to the planes owner who stated that there was a 'primer malfunction' - the mechanics are guessing the primer knob was not locked on takeoff, which could account for the poor performance. Further investigation suggests that this might be a viable explanation for my situation.
I did a bit of research since my original post and located an FAA Advisory Circular that discusses the primer issue: AC No: 20-105B Subject: RECIPROCATING ENGINE POWER LOSS ACCIDENT PREVENTION
AND TREND MONITORING. A quote from the maintenance section of this document states:
'Engine Primer. The primer is a simple system in which raw fuel is drawn from the engine supply line and injected into two or more of the engines cylinders by means of a small hand operated pump. If the primer pump handle is not locked in the closed position, raw fuel will continue to be drawn into the cylinders by the suction created in the affected cylinders during the intake cycle. The engine will run rough at low RPM, mimicking magneto problems,
but will smooth out above 1700 RPM. The exhaust at low RPM will be black and smoky, and the fuel/air mixture will be extremely rich in the affected cylinders. Leaning the engine manually may restore smoother operation but excessive leaning will raise the cylinder head temperature in the cylinders not equipped with engine primer lines. A similar operating condition may exist if the 0 rings in the primer pump are nicked or cracked which allows fuel to pass the 0 rings and into the cylinder even if the pump handle is stowed and locked. If this condition is suspected have a certificated mechanic check the primer system.'
This sounds very much like the situation I experienced in the Warrior.
Further investigation of the Sensenich 74DM6-0-60 prop, which is installed on the Warrior, revealed the max throttle 'static' RPM should be between 2350-2450. The Warrior POH supports this info.
Additionally Lycoming engine documentation indicates that every model of the O-320 series 160 HP engine that they manufacture has a rated takeoff rpm of 2700.
I'll be sure and keep an eye on static and dynamic RPM during my next flight.
Thanks again to all who replied.
