PT20J

Section 3.3.4.1 in the G5 manual: Activating ROLL commands wings level if bank <6 deg ; Holds current bank angle if 6 to 20 deg; holds 20 deg if bank angle is >20 deg.

OK, lets' sort this out. First, the problem is electrical because it happens when you turn on the master switch and not the standby vacuum pump or engine. Second, it's not the BK attitude indicator because that is a vacuum instrument, not electrical. As an aside, it is most likely a KG 258 and likely still drives your KAP 150. Blowers and motors turn slower than gyros and sound more like vacuum cleaners. Electric gyros spin really fast and when the bearings go out they sound more like a whine and/or a grinding sound. If the sound is coming from the instrument panel area it might be the turn coordinator which is electric. Or it might be a bad avionics blower as already suggested. My bet would be that the defroster blower is running. There is a little microswitch behind the console that connects to the control cable with a wire "whisker" that can become detached. It's easy to check, just pull the defroster circuit breaker. Skip

I flew floatplanes Part 135 for a couple of seasons in SE Alaska where the weather is famously terrible. One of the most challenging flights was often the 12 minute flight between Ketchikan and Metlakatla. One of the older, wiser and not-so-bold pilots taught me that if it’s barely VFR at each end, somewhere in the middle it’s probably worse. Not a bad way to think about any flight, I think. Skip

Hey, Don, a couple if questions: Do all GFC 500 installations require the G5? I thought that the autopilot logic is distributed between the G5 and the servos with the mode controller just being a “dumb” user interface. The ROLL mode holding bank is interesting. In my experience, autopilots without a turn knob hold wings level in roll mode. Do you find this feature useful? Thanks, Skip

Here's what I did: I bought the cleanest, latest model airframe I could find/afford with a run out engine and avionics that I could live with. I replaced the engine with a factory rebuilt. Lycoming IO-360s rarely make TBO unless they fly a few hundred hours/yr as the lifters corrode and cause the cam to spall. The factory installs roller lifters in its new and rebuilt engines that should fix this. At this point I had a solid airframe with a new engine and good IFR capability: Aspen PFD, GNS 430W, KAP 150 AP to which I added a GTX 345 transponder for ADS-B and an iPad yoke mount with a USB power cube for a moving map. Today there is a bewildering array of avionics available. It's very easy to get panel envy and put a LOT of money into a 25-40 year-old airplane that you will never get back. It's certainly fine if you want to do that, but I'd think it through carefully. One of the nice things about Mooneys is that they came pretty well equipped from the factory. Sure some of the stuff is old, but a KX165 for instance works just as well as newer Nav/Coms and you can find lots of used replacements to inexpensively maintain the old stuff. In my case, I only plan to upgrade things that add utility or replace items that are no longer cost effective to maintain. I figure once your cake has an electronic PFD, WAAS, ADS-B In/Out and a 2 axis autopilot, everything else is frosting. I didn't worry about paint and interior during my search so long as the condition was reflected in the purchase price. After all, I figured I was buying an old, used airplane. But do be aware that a new interior and paint job will set you back around $20-25K - more if you go premium. Also, be aware that airplanes for sale frequently have deferred maintenance not all of which will be caught on the pre-purchase inspection which is really just a quick look for deal killers. So, the first year of ownership is often costly in terms of unexpected maintenance. Skip

Hard to tell from the scant info you provided. Where were you when you activated the approach? How did you activate the approach? Did you select VTF? Did you designate DUCER-EDLUC the active leg? Did you edit the flight plan and perhaps eliminate the hold?

Anyone use ZPH?

I think your approach to managing the maintenance of your airplane is a sound one. But, keep in mind that there are few items on a Mooney that really require the expertise of a MSC (control and landing gear rigging come to mind). Much Mooney service is pretty generic and can be done by any competent mechanic. (Also, I've had some pretty ham handed stuff done by MSCs -- there is a shortage of experienced mechanics and the MSCs hire from the same pool as everyone else). Many of us have found it very useful to develop a good relationship with a conveniently located mechanic who is willing to work with us. This allows complete control (which really is your responsibility as owner/operator) in managing the maintenance of your airplane. You can do what you can yourself; get help from the local mechanic as needed; go the the MSC for specialized items. I've noticed the folks that seem to have the most problems are those that just drop of the airplane at a shop (MSC or not) and say "fix it." Skip

It's a little difficult to figure this out from your description. I think you are saying that you were able to transmit and receive but you could not hear yourself in your headset. So, if you only don't hear yourself when you are transmitting, that sounds like a sidetone issue and sidetone comes from the radio. Check to see if it is specific to one comm radio. If you cannot hear yourself when the mic is NOT keyed, that sounds like an intercom issue. Neither sounds like a KMA 24 issue, but perhaps I misunderstood your description.

@Garryowen how good is the SAS on the S-76? Skip

Most mechanics I know only clean the fuel injection screen at annual inspection and frequently don't bother with the oil suction screen unless there is a reason to be suspicious of metal contamination. This is because the suction screen is a pain to get to, and, on many Continentals, the screen isn't even accessible without disassembling the engine so the theory is that it's not really all that important on a Lycoming. But of course, if you don't look you won't know for sure. For any work you want to do on your airplane, it's always a great idea to look up the service instructions. For the fuel injector screen, see section 8-1D of the attached manual. It's pretty straight forward, but note that it is supposed to come out from the inlet side. It's also good to have the O-ring on hand in case it needs replacing. The oil suction screen has a few nuances. See Lycoming SB 480F attached. The first thing to note is that if you find the plug safetied with a cable instead of safety wire, it has never been removed since it came from the factory. When you reinstall it you should use a new copper crush washer. Not noted because it's considered common practice is to put the split side of the washer against the component that is not rotated during assembly -- in other words, the split side goes against the case. If you use anti-seize, the food grade called out will avoid contamination with by metallic components of common anti-seize compounds. Also note that the torque is specified as an angle of rotation. So, as you can see, even simple things can be complicated and that's why it's always best to look it up. I stared at my suction screen for a long time and ended up having my IA do it when we did the annual together. I was amazed at how fast he did it. But... he has done them many, many times and has all the right combinations of wrenches. By far the hardest part was safety wiring the finished job. Nothing beats experience and having all the right tools. Skip 15-338e.pdf SB480F Oil ServicingMetallic Solids Identification After Oil Servicing and Associated Corrective Action.pdf

Now that you jogged my memory, I recall an air show performance in a Schweitzer 300 (articulated rotor) where a steep climb ended with a zero airspeed 180 pedal turn with a descent as you described. So, it’s clearly possible to do this maneuver in a fully articulated rotor system. Is it possible to do it safely with a semi-rigid rotor like a Robinson or a Jetranger? Skip

You’re right; I misstated it. The BSFC increases, but the bhp falls off rapidly and the fuel flow decreases. What I should have said is that you will take longer to get where you’re going and burn more fuel to do it. Thanks for the correction. Skip

Interesting question. It takes more collective to hover than to fly level because a forward component of airflow over the rotor has the effect of increasing the angle of attack for a given blade angle.This is the translational or transitional lift effect. So, if you were to pitch up, the airspeed would drop and the lift would decrease and there would also be a tendency to roll because of asymmetric blade effects as you surmised. It is interesting to contemplate what would happen when it ran out of forward speed and momentum. It's not like an airplane stall where the inherent stability would necessarily cause the nose to pitch down. I'm not sure what would happen, but it probably isn't good. If you were to reduce collective, it would probably go into autorotation. Helicopter pilots don't fly like that though, and it's hard to imagine an experienced pilot doing such a thing. The cyclic is used to get the helicopter moving left, right, forward or back and the collective, coordinated with power, is used to control climbs and descents. Skip

Try an avionics shop that is an Aspen dealer. If they don’t have it they can get it from Aspen. Lots of sellers on eBay buy stuff in bulk and sell smaller quantities, so you could try that also, but this may be too specialized.

Those are excellent observations. If you are getting the same TAS at the same density altitude, you are getting the same thrust horsepower. Remember that thrust horsepower is brake horsepower * propeller efficiency. Also, with a constant speed prop, the efficiency is not going to be dramatically different between 2500 and 2700 rpm. So, what is happening is that the engine is putting out slightly more bhp in your LOP case to make up for the slightly reduced prop efficiency and give you the same thrust hp. Skip

While it's true that the tip drag goes way up when the tips approach sonic velocity (which reduces efficiency) there are other constraints on efficiency. Interestingly, propellers create maximum thrust when the airplane is sitting still, and the thrust decreases as airspeed increases. So, the ratio of airspeed to rpm is an important parameter. Engineers prefer dimensionless parameters because it makes it easy to compare different designs without having to correct for differences in physical dimensions. So plots of propeller efficiency are plotted as a function of the dimensionless advance-diameter ratio (usually just called advance ratio): J = V/nD where V is the velocity (true airspeed) ft/sec, n is the rotational speed in rev/sec, and D is the propeller diameter included as a reference dimension to make J dimensionless. A propeller efficiency curve always has a peak at some advance ratio. The effect of constant speed props is to vary the pitch with airspeed so that the effective peak is much broader. This means that the interplay between rpm and TAS is not as significant as it would be for a fixed pitch propeller. But it is still there. David Rogers did an extensive analysis on the Bonanza propeller efficiency: http://www.nar-associates.com/technical-flying/propeller/cruise_propeller_efficiency_screen.pdf It's a different engine and prop than my M20J, so the results probably aren't directly transferable, but it's an interesting analysis if you are interested in propellers. Skip

There seems to be a misconception about LOP operation among some that if a little is good, a lot must be better. This may be because 'high' CHTs are bad and they cool off when LOP (compared to say 50F ROP), so leaner must be better. But keep in mind that one reason CHTs decrease when LOP is that power also decreases. The horsepower vs mixture strength curve falls pretty rapidly when moving farther LOP. (Conversely, the same curve is relatively flat between peak EGT and 100F ROP which is why the power tables in the POH don't differentiate power output between best economy and best power mixtures). Also, the BSFC curve is at a minimum between about peak and 50-75F LOP and then starts to rise again. This means that if you run leaner than about 50-75F LOP, you will put out less power and burn more fuel per hour to do it. Skip

I didn't mean to imply that there is no relationship between CR and HP. If you take the same engine and increase the CR, it will increase the HP. What I was trying to point out is that there is no formula based on fundamental principles of which I am aware that allows calculation of horsepower based on compression ratio and fuel flow alone for an arbitrary engine. The formulas that originate with APS and others are empirical and based on observations of the characteristics of various classes of real engines. Considering BSFC to be a constant when LOP is an approximation (the curve is relatively flat, but not constant) and relating the minimum BSFC to specific compression ratios is a further approximation based on observation. Taken together they are approximations of approximations. So to answer Parker's question, it doesn't really matter whether you use 15 or 15.1 -- it's not accurate to that level of precision in the first place. Skip

Generally props are designed to me most efficient at climb or cruise. Mooney probably wanted to favor cruising which would normally be done at a lower rpm.

Either you or the examiner (examiner's choice) will designate the specified point before the maneuver begins. From the current ACS: "Touch down at a proper pitch attitude, within 200 feet beyond or on the specified point with no side drift and with the airplane’s longitudinal axis aligned with and over the runway centerline or landing path, as applicable." Skip

A couple of ideas: 1. Try practicing the maneuver with no flaps and aiming for midfield. You don't have to actually touch down if you don't want to, but be able to consistently hit that point. Once you can do that, you can use the flaps to steepen your descent to land shorter. The key is to learn to continuously visualize your glide path throughout the maneuver. Changes to speed and configuration makes this harder. 2. Your approach must be stabilized per the ACS. You should be able to do it with very little slipping if any. If you do need to slip, do it early and get out of the slip by 200' in order to get everything stabilized at a normal approach speed. Skip

That's what I do. I use 2500 because Bob Kromer said that the 201 prop is most efficient at that rpm and I have no reason to doubt him. I can't find a propeller map for my McCauley prop, so I can't verify it. Out west if I need to fly high, I will run peak to get a couple of extra knots sometimes. I don't worry much about the extra fuel as the little four banger doesn't burn that much at altitude anyway. Skip

The red box is a concept. It has fuzzy edges that vary by engine. The APS folks have always been clear about that. But I often see fellow pilots missing the point, taking it as a fact passed from on high written in stone, and then trying to skirt around the red box with undo precision as one might narrowly avoid Class Bravo with GPS. I just think that’s missing the point. A much better way is to understand the underlying principles and use them to figure out how to operate your engine safely and efficiently based on what you are trying to accomplish. I recently asked Mike Busch what power he sets for cruise, and he said he had no idea. He guessed it might be around 65% but he didn’t really care. He had figured out combinations of MAP, rpm and FF for climb, descent and cruise that balance his objectives of speed, efficiency and engine longevity and the actual horsepower produced was irrelevant. He also pointed out that people often comment when flying with him how little effort he expends setting power and mixture. Just another point of view... Skip

I always find these discussions interesting and slightly amusing. There seems to be a lot of interest among pilots to figure out how much horsepower your engine is developing. I wonder why? Do your ever calculate how much power the engine in your car is producing when cruising down the highway? Perhaps the reason is that we are conditioned since our earliest exposure to airplanes by the power charts in the POH. All that is really necessary is to find operating points -- i.e., combinations of MAP, rpm and FF -- that get you what your want (speed, economy) and won't damage the engine. If you look at the way the airlines operated the radials at the end of the piston era, you'll find that they cruised at low power (usually around 55%) and LOP for economy and engine longevity. If you cruise ROP, you get more speed and less economy and need to watch your CHTs. Some have found that they can cruise at 80%+ power when LOP with CHTs below 400F. There is a wide range of operating parameters and the horsepower produced is only part of the equation. The only accurate way to determine horsepower produced is with some sort of direct measurement device. The big radials had built in torque meters (interestingly calibrated in BMEP - clearly designed for engineers). The power settings in the M20J POH may be the most accurate as LoPresti measured torque to determine the actual power for the 201. His goal was to get >200 mph on 200 hp and he didn't want to fudge the numbers. Anyway, the reason for this digression is to point out that all other methods of determining horsepower are approximations. So, there is no need to be super precise about something that fundamentally lacks accuracy. If you look up the engine manufacturer's data for your engine you should find a Sea Level and Altitude Performance chart for the engine. This is the standard form for figuring out HP as a function of MAP and rpm. It is generally published at best power mixture. Note that this is for the engine in a test cell. It will overstate the power in your airplane because the induction and exhaust system of an actual installation will reduce the power by some (hopefully small) amount. The power falls off somewhat when you lean to peak or lean of peak. Power curves are not generally available for these conditions. If you read John Deakin's writings, you'll find that his opinion -- and generally the position of the old APS team -- is that percent power is overrated as an operating condition. But, the APS folks made an interesting observation: Over a range from slightly lean of peak to perhaps 75F LOP, the BSFC (lbs of fuel per hour per horsepower) is very nearly constant. This leads to the observation that no matter the combination of MAP and rpm, the power can be determined by knowing the BSFC. So, if you can find a curve of BSFC for your engine, you can figure out the horsepower when LOP. If you don't have this data, the APS guys figured out a further approximation. Normally aspirated and turbonormalized engines (usually about 8.5:1 compression) they noted have a BSFC of about 0.39 lbs of fuel per hour per HP, ranging from 0.385 to 0.40. Factory turbocharged engines (usually with about a 7.5:1 compression) are less efficient, with a BSFC of about 0.42 to 0.43. The actual weight of 100LL is 5.85 lbs per gallon: 5.85 /0.39 = 15.0 hp/gph and 5.85/0.425 = 13.7 hp/gph. Note that the hp/gph is NOT directly related to compression ratio -- this is simply a means to (roughly) approximate BSFC based on observations of the performance for a number of engines. Hope this helps. Skip