Q-talk 54 - LETTERS
- Category: Q-Talk Articles
- Published: Tuesday, 31 October 1995 06:11
- Written by Tom Moore
- Hits: 2415
Getting Q-Talk in the mail can be just like getting a letter from an old friend, I just wish you'd write more often!
I saw Paul Fisher's dilemma in Issue #47 regarding his stuck valve in the O-200 and I would like to offer my experience as an A&P. It occurs because of carbon and coke buildup between the valve stem and valve guide. Experts have told me that stuck exhaust valves are caused by:
1. Using fuel with too much lead.
2. Using fuel with not enough lead.
3. Burning 100LL.
4. Burning car gas.
5. Using the wrong kind of oil.
6. Babying the engine, not allowing it to get hot enough.
7. Overheating the engine.
I have experienced several stuck valves over the years and am still not sure what causes it. I am currently adding 4 oz. of Marvel Mystery Oil to every 10 gallons of gas, and I think that it will keep the valve stem lubricated, but I need to put on another 100 hours or so before I make my final judgment.
I do have a method by which you can clean the gummy exhaust stem without removing the cylinder from the engine!
You don't have to go through all of that pain and suffering to remove a jug. In fact the whole job shouldn't take more than 2 hours, even for beginners. (One preliminary caution, if the cylinder has over 1,000 hours you may need a new valve and guide anyway.) Here is my step-by-step procedure:
1. Determine which valve is stuck by removing the upper spark plug from each cylinder. Put your thumb over the plug hole while pulling the prop through. Of course the cylinder with the stuck valve will demonstrate no compression.
2. Remove the rocker cover from the offending cylinder and also remove the lower spark plug.
3. We are now going to move the stuck valve into its normally seated position so we can remove the retainers and springs. Rotate the propeller so the piston is at the bottom of its stroke (BDC). Take about 6 or 10 feet of 3/18" rope (yes, rope!) and stuff as much as possible into the cylinder through the upper spark plug hole. Leave the end out of the hole or you may have difficulty removing it. Now pull the prop and use the piston to squeeze down on the rope and this will pop the valve back out! Note: Do not be tempted to reassemble the rocker box and go fly, the offending valve stem is still dirty and must be cleaned.
4. We will now remove the rocker arm, pin and springs. With both valves in the fully closed position, carefully push out the rocker pin using a wood dowel. Be extremely careful not to damage in the slightest the bronze bushing in the rocker boss. Also do not drop the pin when it comes out, if you do, it should be replaced. It is not necessary to slide the pin out of the intake rocker.
5. Use a valve compression tool (borrow one) to compress the valve spring while holding the piston against the rope, against the valve. Remove the retainer and valve springs. Be sure not to lose the 2 little valve keepers which fit under the valve stem tip.
6. Move the piston back to bottom dead center (BDC) and remove the rope. Using a wooden dowel rod (never metal-to-metal) and a plastic mallet, carefully tap on the head of the valve stem until the exhaust valve drops into the cylinder.
7. Using one of those 3 prong "lost parts retrieving tools" (Sears Craftsman) through the upper plug hole, grab the valve stem tip and pull the stem out of the plug hole. You now have practically the entire valve stem sticking out of the plug hole and you may clean it. Use Hoppes #9 gun barrel cleaner (removes lead), or carburetor cleaner and a fine Scotch Brite pad. You may need to lightly scrape the junk off using a sharp instrument knife. Caution: if you damage the valve stem in any way, the valve must be replaced. Just be careful, you'll do fine.
8. Now we need to clean the valve guide. Do the best you can but be sure not to use anything that will remove any metal from the soft bronze guide. A nifty tool (Valve Guide Cleaner, P.N. 122 $21.80. From Kent-Moore Tool Group, Warren, MI (1-313-574-2332) that I used is perfect to ream out the coke without removing metal. Work slowly and persistently.
9. After all parts are clean and shiny, remove as much of the solvents as you can and lubricate the guide and valve stem with clean engine oil.
10. Now we are going to re-insert the valve into the guide. Take a very strong piece of thread or possibly very light fishing line and loop it around the recess in the tip of the valve stem. Push the valve and thread back into the cylinder.
11. Using a piece of safety wire bent with a hook on the end, fish the thread through the exhaust valve guide, then pull the valve back into place. It will probably help here to use your pronged lost parts retrieval tool to help lift the valve into position. The valve should now move freely in the guide. Keep everything clean!
12. Stuff the rope back into the cylinder a final time to provide a backup while compressing the spring to reinstall the retainer.
13. Reinstall the parts you replaced, being extremely careful to properly seat the little valve keepers and not to damage any bushings. Use a new rocker gasket to protect against oil leaks.
14. Perform a thorough run-up check, check for tightness and leaks and complete your log book entry.
This really is a great way to go, I've probably done it a dozen times on O-200's. All O-200 owners should have one of those valve guide cleaners in their toolbox; your local A&P may not. It's one of those "worth their weight in gold" tools. If you don't want to attempt this job yourself, at least show these directions to your local A&P and insist he do it this way. It will save many hours and $$$!
Sam Hoskins, Murphysboro, IL
Sorry I haven't got any words to you folks for a while. After first flight, there were more questions on configuration and performance than there were answers. However, in an effort to pass on lessons learned I will try to encapsulate what I have experienced with my Q-200.
First flight of Q-200 N557BM was on 27 May 95 at Mojave Airport. I had been high speed taxiing up to the 55 MPH mark for some weeks and was beginning to see the tail lightness and the main gear sashay. My flight test program had been negatively affected by adverse weather in this part of the country. This largely meant high wind conditions at Mojave. Every time I went to Mojave, I'm certain that there was some guy standing camouflaged in the scrub who would flip a switch activating the windmills on the surrounding hills bringing on the big winds. I missed the perfect fly day, 20 May, due to some work I had to do at our local Fly-In. I scheduled with my test team to do the flight on the following day (21 May). When we got to Mojave (0600), the wind was howling. Norm suggested that we try high speed taxiing on runway 25, moving the speeds up a little. So with Bob and Norm in the truck giving close chase we shot 67 and 64 MPH airspeeds on the ground with the wind running about 15 gusting to 20 into our faces. On the first run the tail came off at zero reflex and parked itself about 1 foot off until I cut the power and slowed down. Main wheel sashay was evident with the tail off. On the second run I put about half of my available reflex in and came up a little more slowly on the power and the tail stayed down.
A week later, on 27 May, the weather was cooperating real nice. The Q-200 checked out OK on the ground and we launched the chase aircraft. I initially was set up with Norm's parachute for the first flight, but it just didn't feel right after taxiing on the runway, and I had him come out and get it and replace my original scat cushion. On my first attempted flight (runway 30, 9600 ft by 200 ft wide) I waited for the position call from chase, gave a short five count and advanced throttle whereupon, I started to drift to the left and I called abort. After taxiing around and getting set up again, I made a good straight takeoff (still drifting a bit to the left though). The tail came up and I got the sashay, but I pressed and stabilized. The nose was heavy and I had to hold between 3 and 5 degrees of right stick to get the aircraft wings to the horizon. Scotty Horowitz had briefed me on the left hand roll tendency, but I was not ready for the nose heavy, forward CG condition. The aircraft had checked out fine during the weight and balance. Looking back on the roll condition, however, there is plenty of room on an aircraft under construction to put in a roll trim surface run by a MAC trim system in one of the main wing slot cores outboard of the ailerons.
My eyes were at the horizon the whole time during takeoff (similar to liftoff and hover in an R-22 Helo) and Norm called airborne and Doug slid in under and behind me giving left hand turn instructions to set me up for the abort runway should I loose the engine. Initial rate of climb was about 1500 fpm at 80 mph indicated. I had to flatten that out to about 100 at about 1000 fpm so that Doug could keep his airspeed warning from screaming at him. I also discovered during the climb that there was additional throttle to advance and I went ahead and pushed forward (mistakenly thinking there was more power there - more about that later). The numbers were approximate as I was quick sampling everything. I was completely saturated with doing the flying and observing my situational awareness. In looking back on the first flight, I was almost completely head out. My initial plans were to use no reflex during the first flight.
During the climb I had the distinct impression that I was on the short side of elevator authority and I dialed in reflex which relaxed the situation; I simply ran out of reflex. My reflex is driven by a stick mounted thumb switch controlling an electric linear actuator (through relays) with Bob Falkiner type reflexer mechanism. It works no question and any runaway condition can be stopped by shutting off the master switch. Further, the actuator works like a conventional flap with jackscrew and has electronic position feedback. The other things that works is the larger air filled tailwheel in the custom tailwheel fork for which I provided you drawings. Ground handling performance is good. I gave it a Cooper-Harper of 3 for a taildragger. My chase was excellent in providing clearance, confidence and keeping my attention focused on engine temps (During climb I was seeing 220 F with no oil cooler ... Just the El Reno spin-on). One item of concern was the lack of speed. It seemed as though I were in a slow flight mode as confirmed by elevator position. I can't remember my Tach numbers as I was too busy just flying and our test audio was not recorded. When I got to our target test altitude of 8000 msl I discovered that I was burning fuel faster than my header tank could be filled or maybe (I thought) my sight gauge viewing angle was bad. The transfer pump appeared to be working, but I was headed down to expedite a landing. I was fuel low and I didn't think there would be time for a once around or practice approaches. With chase tight on my tail I shot the landing, bounced twice and rolled out on the third. Nothing wrong turned up in post flight. My son and I pulled the cowl immediately after getting it back in the hangar and everything looked good. Doug Shane had theorized that maybe my prop wasn't right for the engine (It's a 58 inch 70 Mahogany prop by PROPS INC) or I was having turbulence off the engine inlet because it was sharp. Anyway, I survived the first flight (Mission Elapsed Time 5) and the plane looked good, so I figured I would schedule the next weekend.
The second flight was on 4 June from runway 07 (7000 ft by 75 ft wide). I had ballasted the aircraft with 50 lbs of no. 9 birdshot in the baggage compartment of the aircraft in order to drive the CG into a more favorable condition. I was at about 30% main tank fuel. I had the same chase support as the first flight. We had briefed a full schedule of test cards and a plan to fly for 1 hour. The wind was not, however, favorable for the long runway. On takeoff, I advanced to full throttle travel (Mistake!). On climbout my chase requested I give him some more speed and I remarked that this was all I had at about 90 mph! I was only climbing at 900 fpm and I was beginning to work at solving a problem. I just wasn't sure what I had. The signs are all over the place when you look at the chase video and listen to the audio. Climb was poor, on airspeed tests were poor and I was seeing only 2100 rpm. The fuel state was getting bad, too; again the transfer pump was not getting fuel to the header in any significant amount and my attention was almost 50% flying and 50% looking at the right hand side of the panel trying to figure it out. I advised Doug that I could no see no visible sign of fuel transfer and that we needed to get down soon. Doug escorted me to a High Key entry to runway 12 (9600 ft by 200 ft wide) with a slight crosswind. Doug and Bob had hacked the descent and were intent on getting gliding data during a 360-degree turning approach. I was a little more desperate than that and had to deviate from the test condition after taking another look at the fuel state transfer on, but no fuel getting through. I made the landing and rolled out without incident. Again, everybody said good job (you did good) and theorized about what the problem might be. After everybody left that morning, I did a little more looking into the fuel system. Guess what I found? The Purolator fuel filter downstream of the facet fuel transfer pump was 90% clogged with foam debris from the main tank and the facet pump went glubbb, glubbb, glubbb when you turned it on. And you know what else? When you are pulling high flow rates from the main with your tail on the ground the fuel quality is better. When you are pulling high flow rates from the main with your tail down (you know, like when you are flying) all the crap goes into the sump where the pickup and screen are and you get poor fuel quality. Solution, either keep cycling the fuel during ground test with the tail high or figure a way to vacuum all the FOD out of the tank!
Since these two flights I have cut into my cowl and my air box. I've made several more engine runs and learned a lot more about how this engine/airframe assembly works. I'm still experimenting with it. I called the Ellison folks about the Injector/Engine problems, but they are not really focused on some of the issues, which I am seeing. Ellison is quite responsible and makes a good product. The Q-200 configuration is a tight engine installation and the variation in prop types make it difficult for Ellison to really give me a solution to my performance problems.
I have added about 30% more volume to my air box and noted no improvement in rpm. With three different air boxes (Aluminum boxes of two different sizes and a fiberglass box which conforms to the internal mold line of the lower cowl) and with nothing but a filter attached to the engine, I was able to get a maximum rpm of 2300 static with the tail tied down at 2787 msl (Mojave). This matches the static RPM value quoted in Firewall Forward. Advancing the Ellison farther than this causes a fuel rich condition with a 200-rpm drop in 3 seconds and noticeable smoke from the exhaust. 2100 rpm from an O-200 is 43 HP according to the O-200 Overhaul Manual folks! Norm Howell has a saying "I love my airplane/I HATE my airplane." It fits.
(1) Having chases and data recording are good things.
(2) Do lots of engine runs to full power with your tail tied down.
(3) Perform fuel transfers from all flight attitudes.
Safety Considerations: Being a family type guy with a mortgage to pay on, I took out EAA accidental insurance and also filled out an EAA flight advisor form for my aircraft insurance company. Throughout my test flights, I am committed to wearing my Nomex flight suit with Nomex gloves and David Clark K helmet. My jet helmet wouldn't fit under the canopy with good clearance and impedance matching was a problem. For you guys out there who used to race dragsters ... those racing firesuits, shoes and gloves are better than what the military uses so - wear 'em if you got 'em. I carry a handheld ICOM as a backup. I carry emergency egress tools a 3/16-nut driver to loosen the canopy latches if they get stuck and a Cold Steel Recon Tanto Combat Knife to cut through the fiberglass sandwich walls or Plexiglas if I've got to get out in a hurry. Norm Howell carried my ball peen hammer in case he needed to smash my canopy to get me out.
In addition: For you guys that haven't flown something that you have built before and want to know what it feels like at least from my perspective ... I was too busy flying to notice. I didn't have a good time, I didn't get scared and I didn't get to look around and go this is neat! I was working the whole time and I was busy. Roll control is delightful, pitch is heavy, but sensitive, and rudder is powerful. Ground handling is something between a tricycle gear and taildragger. With my mains aligned straight ahead and my big air filled tailwheel, I think the design works well.
Prior experience flying an Ellison equipped T-18 convinced me that there was no problem with this type of fuel metering device. It should be noted, however, that the airplane I flew had a lot more room under the cowling than my Q-200.
Klaus Savier once cautioned me at a party to be careful with the Ellison Throttle Body installation, as they are frequently problematic. In a recent phone call, Klaus passed along that he continued to have some difficulties with the Ellison and that he doesn't let anyone else fly his Eze due to some critical adjustments that he must make during takeoff.
Gene Sheehan has passed on to me advice that the engine inlet lip on my lower cowl was too sharp and may cause turbulent effects to the Ellison Throttle Body Injector (EFS-3). He says that the propeller, which I am using, is fine for the flight-testing I'm doing, but should be replaced with a more stable hardwood when I begin making cross-country attempts. Sheehan also remarks that the size of the original air box I built is perfectly adequate for the EFS-3 and that air box size is less important than maintaining non-turbulent flow. It is also interesting to note that the Sheehan Q-200 does not have the characteristic induction bulge on the lower cowl and pulls its engine air from a very small NACA duct on the face of a more Q-2 type mold line with no carb heat installation provided. Gene Sheehan further relates a story of fitting one of the early Ellison Throttle Body Injectors (EFS-2) to his O-200 early in the Q-200 days. He says that the Ellison folks came down to observe the installation and the resulting performance. He remarked that even the EFS-2 provided more air than the O-200 could use. He says that Ellison later recommended that O-200's use the EFS-3. Both the EFS-2 and EFS-3 would not allow full throttle "Max. Venturi Open" operation as satisfactory atomization would not be possible for the O-200 at this point. He remarked that Mike Melville has seen the same thing. Gene Sheehan advised to continue ground running the engine, determine the max. power throttle position and effectively "throttle stop" it there.
Many thanks to Paul Fisher, Dick Shapley, Bob Rowin, Art Jewett, Astronaut Scotty Horowitz and Gene Sheehan for passing on valuable tidbits of flight information on the Q-200. Thanks to you Jim for keeping it together all these years. We continue to flight test.
Brian Martinez, Quartz Hill, CA
(Ed. Note: Brian has sent in some additional flight test info and we'll have that in a later issue.)
Brian Martinez heading out for a test flight.
The following is a report that Q-TALK asked Art Jewett to put together on his experience with the NAVAID DEVICES autopilot that he has installed in his Q-200, N2AM.
In January 1990 we took our first long cross-country flight in N2AM. In western Kansas we encountered high winds and pretty rough air. This lasted all the way to our Denver destination. In spite of careful attention to adjusting pitch and roll trims, the airplane required full time stick and rudder to offset gust upsets.
Attempts to use my right hand for anything other than flying the stick resulted in considerable deviation from normal flight attitude. I was no good at across the body left hand flying in rough air. Tuning the radios was difficult, folding maps and calculating ground speeds was next too impossible. At that date loran still had its mid-continent gap so our unit was of little help. On our return home we ran into poor visibility due to blowing snow. Deviations into southern Nebraska were required to get thru. It would have been nice to execute turns around and thru that stuff with a wing leveler.
It was clear that N2AM's occupant comfort and cross-country utility would be considerably enhanced with a wing leveler, heading tracker installation. Feb./Mar. 1990 were spent looking at alternatives to do that. Most of the systems I was able to examine were based on vacuum driven bellows actuating control surfaces. Control of airflow to the bellows was achieved thru heading bugs and turn and bank (T/B) instruments. I didn't like the complexity of all those hoses, cables and valves.
I was attracted to Doug Spear's NAVAID DEVICES all electric system. After several question and answer sessions with Doug, we purchased his unit at Sun 'N Fun '90. The unit could operate as a T/B indicator, or T/B plus wing leveler, or T/B plus heading tracker. It was capable of tracking any analog output and was switchable to allow tracking of my panel mounted receivers. My initial installation was switchable between the VOR and loran receivers. NAVAID DEVICES AP-1 is panel mounted (I replaced my T/B with it) with an electric cable connecting it to a servo unit that I mounted on a small platform secured astraddle FS94 bulkhead. (SEE PHOTO BELOW)
The servo is mechanically connected to the QCSA-3 aileron bellcrank by fabricating a 2nd bellcrank with two horizontal and one vertical arm, all of the lengths equal to QCSA-3. The horizontal arms are connected on top of the aileron rod ends connected to QCSA-3 (this eliminates the need for the AN903-3 washer). The NAVAID DEVICES servo unit drive arm is then connected to the vertical arm of the new bellcrank (rod and rod end supplied by NAVAID). The AP 1 unit is electrically connected to aircraft power, and avionics, along with power and signal connections to the servo unit. That's it, the installation is really simple, but does require access to the back face of FS94 which is no problem if your fuselage splits.
I had some difficulty with the system. Initially it just would not operate. After several phone calls to Doug to discuss results of tests he requested. Doug asked me to do some testing by simply replacing each of my components one at a time with components from a new set he sent me. The swap outs were not required to find the problem. Examining the replacement units showed me that two leads were reversed on my AP-1 to servo cable. That was changed and presto my unit worked. Doug tells me that the installation instructions have been modified to avoid this problem. My unit did not require changes in aileron null position or clutch slip pressure from the factory settings. The NAVAID DEVICES brochure describes what they think are major benefits of an installed autopilot. After five years of use, I agree with what they say. If our trips had continued like the initial one to Denver, there would be fewer hours on N2AM. It's hard to put a price on that. There are lots of things on my panel that I would give up before the autopilot!
During the early flights we had lots of trouble with poor loran geometry and signal to noise ratios, resulting in shutting down any loran navigation information. In an attempt to get info back we developed a technique of turning off all electrics including the alternator, except the loran. We found that in flight we experienced un-commanded wing waggles if the autopilot was operated on battery power only. That was a neat safety feature -- low voltage warning for autopilot flying, indicating an alternator failure. By early 1994 we began to have un-commanded wing wobbles all the time. That wasn't so neat! We suspected an autopilot malfunction, as the alternator looked good. Another call to Doug. He was convinced the problem was low voltage at the servo unit, but agreed to send me a tested loaner set to help isolate the problem. Again the loaner set proved the problem was in my wiring, as both autopilot units acted the same way. Doug insisted that we test the voltages across each connection point from the battery terminals to the servo. To shorten a long story, with the help of an EAA friend and his oscilloscope we found the cause. The avionics master bus lead wire had only three unbroken strands of wire carrying the entire load. This caused a big voltage drop to the avionics bus under full load. The break occurred at the ring terminal connection point. Wonder where we might have been when the other three strands broke, leaving us with no avionics. The NAVAID DEVICES autopilot does serve as a low voltage warning.
In Oshkosh '94, we had decided to switch our loran to backup navigation and go to a GPS for primary. In discussing this with Doug at his booth we learned that the inexpensive portable GPS units would not provide the electronic output required to drive his autopilot. Seems that the U.S. Government regulations require GPS units to be panel mounted if they are capable of driving a standard autopilot. We decided to wait. By spring of 1995, PORCINE ASSOCIATES of Menlo Park, California was offering a GPS Smart Coupler that would interface a portable GPS unit with an autopilot. GARMON was offering a GPS-90 as a low cost portable moving map unit. At Oshkosh '95 we found Jim Ham, a fellow Q-200 builder and the designer of the Smart Coupler, was sharing a booth with NAVAID DEVICES. Doug agreed that combining the GPS Smart Coupler with the GPS-90 would drive his autopilot.
On the way to Ottawa '95 I found that minor deviations from course were resulting in sharp-steep banked turns for correction when I used the Smart Coupler and GPS. I was not used to this, as the Loran changes were very shallow and gradual. Reading the Smart Coupler instructions tells me that I may prefer one of the other options available for a wider course line. Mine was initially wired to 1.25 nm with options available for 2.5 nm, 5 nm, 10nm.
Art Jewett, Louisville, KY
That time of year again already! Hope you had a great Christmas. Enclosed are my annual subscription dues and my annual builder's tip.
To provide good cabin ventilation, I provided an air outlet path that would place the outlet in the lowest pressure location on the fuselage ... the top of the fuselage just behind the canopy. To do this, I modified the lip on the rear of the canopy that overlaps the fuselage above the main wing. I contoured the lip so it is about 3/4 inch above the fuselage over a distance of about 6-8 inches. I extended the raised lip a little further aft as well, just to reduce the chance of rain getting in while the aircraft is parked.
Even though my air inlets are rather poorly shaped, I have very effective ventilation.
Another suggestion I have is regarding fuel systems. The plans indicate that the fuel drain and engine feeds come from the same place. I believe that the drain sump should be at the lowest location in the tank when the plane is at ground altitude - i.e. the aft of the main and header tanks. This is where any water will collect. However, in order to maximize useable fuel the engine feed should be at the lowest point with the plane at flight altitude (i.e. W.L. level).
Hope these tips are useful for new builders. Thanks again for a great fly-in at Ottawa. I hope C-FQQQ and I can make it three years in a row next September.
Kimbull McAndrew, Box 0, Site 19, RR #1, DeWinton, Alberta T0L 0X0
COPPERSTATE DASH AIR RACE
On October 13, 1995, Dave Carlson from Tucson, AZ flying a Q2, won his category (aircraft with 75 HP or less) in Aircraft Spruce & Specialty's first annual Copperstate Dash Air Race. The race covered a 305 nm course from Apple Valley Airport in California to Coolidge Airport in Arizona. Dave completed the race in 2:52:44 with a speed of 105.94 kts.
You can order a PDF or printed copy of Q-talk #54 by using the Q-talk Back Issue Order Page.