PT20J

M20J, 2450 lb takeoff weight, flaps up. I held the airplane on the ground with elevators in a constant 5 deg nose up attitude (the normal resting attitude on the ground) during the takeoff roll. It lifted off without rotation at 76 KIAS.

When mine did this, the Autopilot State column showed: Fail / Attitude comparator / 00002004 00000800

One thing to check is the pitch/roll calibration of the GMC 507. If the GMC AHRS doesn't agree with the PFD, it causes a monitor fault disconnect.

I've got a 406 ELT connected to the GPS for position, a PLB, an inReach, a cell phone, and a VHF handheld. If I get stuck in the bush, I really want to be able to call someone to come get me.

RSA servos don't meter fuel according airflow below about 1200 - 1500 rpm because there isn't enough air flow through the venturi and into the impact tubes to create the necessary differential pressure across the air diaphragm. There is a spring in the regulator that holds the ball valve off the seat to let some fuel flow into the metering section but the mixture at low throttle settings is controlled by a mechanical linkage on the throttle to an idle mixture valve. At high density altitudes, as the airplane slows down on the rollout with the throttle closed, there isn't enough air and the mixture will be too rich. You cannot really fix this by manual leaning during the let down because you'd have to lean so aggressively that the engine wouldn't run above 1000 rpm. The solution if it starts to die is to just give it a little throttle. If it's doing it all the time, adjust the idle speed and idle mixture.

There are a lot of variables. Eliminating measurement error would be helpful when making comparisons. tas_fnl3.pdf

When you normally prime, do you open the throttle at least 1/4 travel? If not, the idle mixture valve will greatly reduce fuel flow. If you left the throttle open after the failed flooded start attempt and then later primed it as usual a lot more fuel would flow than you were expecting if you prime for the normal amount of time.

It’s summer

I accidentally activated my ACK E-04 406 ELT in my metal hangar a while back. I shut it off when I discovered the error so it was on less than a minute. Within 10 minutes my mobile phone rang asking if I needed assistance. I asked them to confirm my location and they had my exact lat-long. They work pretty well.

THIS^^^^ weights are usually right but you have to follow the procedure in the service manual and often mechanics unfamiliar with Mooneys use a generic procedure.

Well, the problem with the video is that even though the engine is hot, Don repeatedly shuts down and immediately restarts. That’s the easiest condition because the whole problem is the variability in the amount if fuel in the lines between the flow divider and the nozzles and when you immediately restart, the lines will still be full.

Wow. Just, like, wow.

Look in any basic aerodynamics text. At cruise speed parasite drag predominates, so a first order approximation ignores induced drag (which will, of course, underestimate the total drag). Parasite drag increases as the square of true airspeed. Power required to overcome parasite drag varies as the cube of true airspeed.

It helps to understand a bit how the RSA fuel injection system works. It takes some of the Voodoo out of it. During cruise operation, the airflow through the servo controls the amount of fuel delivered to the nozzles to maintain the mixture set by the mixture control. But, at engine speeds lower than around 1200 rpm, there isn't enough airflow through the venturi to meter the fuel properly. Thus, the servo has a manual linkage connected to the throttle that controls the fuel flow at part throttle openings. Setting the throttle for approximately 1000 rpm (it doesn't have to be exact) will allow enough air and fuel through the servo for starting, but it still has to get to the nozzles. Normally, the lines between the flow divider and the nozzles are full of fuel. On shutdown, when the fuel flow stops due to the mixture control being placed in ICO, the pressure at the flow divider drops below 2 psi and a valve shuts off fuel flow between the flow divider and the nozzles to ensure a clean shutdown. If the engine is cold, fuel remains in the lines between the flow divider and the nozzles. If the engine is hot, fuel vaporizes in these lines and they eventually empty. So, if you shut down a hot engine and immediately restart it, there is no problem because the lines are still full of fuel. If you wait long enough, the lines are empty and it will take a lot of cranking (or a little prime) to fill them before the engine will start. Somewhere in between and there may be enough fuel in the lines to start the engine, but it will quickly die as the fuel is used up until the lines refill.

Kind of sounds flooded, and if you usually prime after a short taxi and it has been reluctant to start I would try not priming in the future. All your attempts may have flooded it more and then it takes a lot of cranking with the mixture in ICO and the throttle wide open to get it lean enough to fire. You can determine if it's really flooded badly by getting out and checking to see if fuel is draining out the sniffle.

A Cherokee also has a laminar flow wing

I think you are exactly right. If I use 5 lbs of pull my airplane takes off at about 65 KIAS. If I add enough elevator pressure to keep the nose wheel on without letting the mains get so light that it wheelbarrows it will take off flat at some higher speed. Probably less than 90 KIAS. I'm betting on about 75 but I'll have to try it someday. This is all with the flaps up. It will definitely wheelbarrow with takeoff flaps because of the effective angle of attack is higher.

Well let's think about that. If you hold it on the runway it will wheelbarrow. If you hold 5lbs back pressure it will take off maybe around 65 knots. This implies that there is enough elevator control to keep the weight distributed between all three wheels as the airplane accelerates. Since it sits at a positive angle of attack, it will eventually lift off, but it should be possible to hold it on the ground well above normal takeoff speed. Thought experiment: How fast was Bob Hoover flying when he did successive one wheel landings with a climb and roll between touchdowns?

Maybe, but I think there would be very little wear on the sprockets if the chain is properly lubed so that the rollers roll frequently. But, for sure, the most important thing is to have some sort of lube on the chains.

I cannot for the life of me understand why Mooney says to lube the chain with grease. A chain needs a less viscous lube that gets into the rollers. On mine, I had to replace the hardened brass bushing for the trim wheel shaft that had worn from never being lubed. Also, there was some eccentricity between the top and bottom sprockets so the chain tension had to be adjusted as a compromise between too loose at one point and too tight 180 deg opposite.

That’s a good thing, right? Have you calculated your ratio of maintenance hours to flight hours? (If not, don’t. It’s disheartening).

You could check the p-lead shield. If it is only grounded at the mag and was not reconnected when the mag was reinstalled then it may be floating when it should be grounded.

Sure. Set up charge plus minimum production run. Good luck. There’s another thread where someone is negotiating with Mooney for a run of 40:1 gears for Dukes actuators and most responses were along the lines of “I’m in unless they cost too much.” There is a reason why Mooney owners have a CB reputation.

That part noted at the end of the thread reference by @1980Mooney is the mechanical down stop. In the event of a failure of the down limit circuit, it keeps the motor from overrunning and bending the push-pull tubes. I know it is on the Avionics Products/Eaton actuators. I think it’s also on the Plessey actuators.