23rd December 2012

Time away & more maintenance

Until this weekend, there hadn’t been any flying for over a month…work schedule combined with lousy weather patterns kept the door to the sky closed for me.  Friday was the first day of my “Christmas vacation” (I’ve taken a few PTO days so am off work from 12/21 – 1/1; a common practice because the students are all away for the break anyway).

During the downtime, I was able to sneak off to the hangar a couple times, during which I disassembled the induction system, and removed the fuel servo.  I found that the servo’s inlet filter had some debris in it, so that was removed and cleaned, and the area beyond the filter inspected as best I could visually, through the inlet hole.  Filter replaced with a new O-ring.  I also talked with Don at AFP, and subsequently did a careful cleaning of the boost venturi (the gold bullet piece in the servo’s air passage) with a Q-tip and brake cleaner.  I also replaced the O-rings on the fuel pump inlet & outlet fittings.

The previous weekend, I was able to get the fuel servo and induction system reinstalled — so Friday dawned clear, and it was off to the airport for post-maintenance testing.  A ground runup indicated no leaks or other concerns, so I recowled the plane and went up.  No concerns on taxi or takeoff, I headed up to New Richmond for some cheap fuel, then came back to Red Wing and did some pattern work.  No stumble/miss at all; but whether this is related to the work I did, or simply the lower OAT is unknown yet.  Allison stopped by and we went for a jaunt across the south suburbs of the metro and back.  It was the first decent day in awhile, so plenty of traffic to keep eyes out for.

In anticipation of some XC time over the holidays — assuming the weather cooperates — I popped out to the airport again to do some work on the plane.  I pulled up the floor pans, hooked up the roll trim springs, and installed the trim lever.  I also installed the fittings for the Gust Buster system I bought awhile back, since we may be parking away from home for a few nights.  Put the set of cowl plugs I got from Van’s in the travel bag, along with the PVC tube chocks I worked up on Friday evening.  Should be good to go…

Things still on the “to do” list include adding a cooling shroud to the fuel pump, and adding Van’s oil cooler shutter; both of which I have on hand.  I currently have 3 strips of tape on the oil cooler, and it’s almost enough.  And of course, finish the install and fiberglass work on the gear fairings…!  Once that’s all done, time to deal with the prop pitch.

I tested out a Stratus ADS-B receiver I picked up used on Friday; seems to work fine.  The downside is that you need to leave Foreflight on the whole time; it doesn’t process any data received when the app isn’t active, so be careful handing the Ipad to a passenger to let them play DJ.  It’s helpful to be able to see weather from airports that have their AWOS on the VOR frequency, though, since I have no NAV receiver.  I’d like to have the traffic component too, but without an ADS-B Out box, it’s not too useful.

On a less positive note, future panel plans may be changing…it appears that AFS has now discontinued all the 3000 and 4000 series displays, in favor of the 5000 series.  I understand the business and technical reasons for that, but unfortunately I still have a big hole in my panel where a 4500 is supposed to go.  I posted a question on the AFS forums about whether the 4500 would still be available for any period of time…otherwise, my best hope would be to try and pick one up later, from someone selling theirs for an upgrade.  I do hope they’ll fix the known bugs in the box before discontinuing development…

Christmas flying plans are made, now just playing the wait-and-see-weather game.  We’ll be headed north somehow, whether on wing or wheel, for Christmas, then may be headed south toward warmer parts for a couple days afterward.  Safe travels to all!

Posted in Maintenance | 1 Comment

5th November 2012

Getting up & going

Since finishing up the flight test hours a few weeks back, we’ve done a bit of flying in the plane.  Allison went up for her first flight the same evening I finished the 40 hours, just a local flight down the Mississippi, across to the farm, up and around our house, then zipped up to Hastings to circle her school, out to Ellsworth, and back to the field before sunset.

In the following weekends, we planned some short XC flights to visit family & friends, but each has so far been cancelled or shortened by weather.  Such is the flying life in fall –  early morning departures were been pushed back to afternoon while waiting for clouds to clear.  But with the speed of the RV, it was still possible to make the trips and squeeze in short visits, still getting back before nightfall.  One trip had us flying south of the cities at twilight…quite beautiful with all the lights laid out below; the cellphone camera did it no justice.

First, we headed up to the Superior WI area to visit Allison’s sister & brother-in-law, and premiere the videos we put together from all the footage I shot at their wedding earlier in the fall.  The next weekend, we popped up to Fergus Falls MN for a late lunch with her parents, and show them the videos.  (Ipad: flight bag, mobile office, and video player all in one.)  We’ve twice tried to make Madison WI to see a college friend, but cancelled both times.  No flying this past weekend due to weather and work commitments; I might be able to sneak away for a day this week if the weather turns decent.

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16th October 2012

Flight testing wrapup

To close out the flight testing, I juggled ballast around the cabin to explore the range of CG loadings.  With all the typical loading scenarios that I worked out, I can’t put the plane outside the envelope unless it’s over-gross; it never really gets close to the edges.  So, I worked weight back into the baggage area for aft CG testing, and repeated the stall series for good measure.  No surprises.  She really flies nicely.

With the temperatures turning colder as winter comes on, I put a strip of aluminum tape on the top of the oil cooler, to try and raise the oil temps up.  Since the variability of fall is unpredictable, I want to approach blocking it off in increments, so it doesn’t get too hot.

With just over 40 hours on the clock, I brought the logbooks up to date with the various engine maintenance, oil changes, replumbing, and so forth that had been done during the test period.  Then, wrote out and signed off the Phase I completion entry.  Free at last!

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15th October 2012

EFIS display quirk

I’ve noticed a quirk in the AFS 4500 display, and after some experimentation, have identified the specific conditions that produce it.  I remembered to grab some screenshots on a recent flight, hoping they will be useful to Rob and the rest of the AFS crew for figuring out what’s behind it…

The bug is related to the VP-X system display page (accessed by pushing ‘Check’ once): whenever that page is displayed, alongside any page that contains BOTH the course AND bearing needles on the display, neither the course needle, bearing needle, or the colored status indicators for the VP-X loads are displayed.  The pitch indicator wings and flightpath marker also disappear.  In addition, the bar along the bottom of the screen with the button/knob legends turns white.

If only the course OR bearing needles are displayed, everything displays normally.  It is only when both needles are selected, that the problem exhibits.

(click any image for a full-size version)

PFD screen with CRS and BRG needles:

Same screen, with VPX page selected:

Split PFD/Map screen, with CRS and BRG needles selected, and VPX page displayed:

Split PFD/Map screen, with only CRS needle selected, and VPX page displayed, all is well:

Split PFD/Map screen, with only BRG needle selected, and VPX page displayed, all is well:

Map page, all is well:

6-pack page (4 with VP-X displayed), all is well:

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14th October 2012

More flight test notes

As I’ve tried to fill up all decent-weather daylight hours with flight testing, the days have continued to get shorter, and the other activities that go along with the arrival of fall have begun again, as well.  Which is a long way of saying, I’ve gotten rather lazy about posting my flight test notes after each flight.  So this entry covers the last 2 weeks worth.

Things are generally going well, and I’ve continued getting to know the plane, and become more and more comfortable with how she flies.  I’ve done a moderate amount of pattern work (though I could use more yet) at the various airports, and can consistently land in a reasonable distance.  I’ve done simulated engine-out drills over the airport (altitude loss was 6-800′ per 360° turn).  Steep turns, dutch rolls, more stalls in various configurations, and so on.

After previous adjustments to the heavy left wing, I’ve flown the last 3 flights with 120 lbs of ballast in the right seat, and I’m happy to report that in the current config, with the ballast, it flies pretty much hands-off straight with an equal fuel load.  So, with a passenger, it’s balanced.  I’ll install the roll trim linkage soon, and unload the ballast.

I’ve done climb rate testing, and though the data isn’t as precise as I would ideally like, I’ve called Vy (best rate) to be 85 KIAS, and Vx (best angle) to be 75 KIAS.  In reality, the pitch angle below 80 is so steep that I wouldn’t want to go there…it’s impossible to see over the nose.  I usually end up climbing out around 100 KIAS, keeping the nose just below the horizon for visibility.  (I expect the speeds to change when we get the prop re-done.)  ROC at ~3000′, Vy is around 1450 FPM.

Messing around with economy power has been fun, too; how much fuel does it take to go along at 90kt, for example.  The EFIS uses groundspeed to calculate fuel economy (mpg), so any head/tail wind is factored in; I had a 23kt tailwind today at one point, and was showing 48 statute mpg at 143kt GS (120 ktas, 3.5 gph)…

Coming back to the airport at twilight continues to be a highlight — watching the sunset, and the lights winking on in small towns and farms, the headlights of cars on the county roads below.  Then, coming back into the pattern and clicking the mic to bring up the lights, I’ll never get tired of that view.

The engine stumble has essentially cleared up with the lower OAT.  Now, I’m trying to raise the oil temps, as I’m getting only 160 or so degrees.  I taped off part of the oil cooler which helped (mid-140′s to 160), but I need to add another strip and see what happens…looking to get over 180.

The nose seal weep that disappeared after 5 hours has reappeared, and weeping slightly more than before.  Not a lot of oil by any means, and not noticeable at all on the dipstick, just enough to make a bit of a mess.  Plan is to do the seal when I pull the prop for repitching; I already bought a couple new seals, and have the adhesive.

For some reason I’ve put off doing the maintenance logbook entries as I go along; fear of doing them wrong, I guess.  I was going to do them all tonight, but forgot the logbooks at the hangar.  Instead, I typed ‘em up on the computer, so at least I have all the numbers and such when I go to write ‘em in.  Now at least I don’t need to worry about forgetting something.  I may keep the electronic log going in parallel, too, since it’ll be searchable and readable (let’s just say my handwriting leaves something to be desired)…

I’ve worked on assembling a list of items that I want to put together for an onboard tool/spare kit, to allow repairs to be made away from home on trips.  Now I just need to track down all the stuff for an affordable price.

Allison is on break this coming weekend, and wants to go for a ride; she’d like to do some hops around the state to see her various family and check out the plane’s comfort level (it’s an easy 1:15 plane ride to her parents, or ~4 hrs in traffic on I-94).  I have just a few hours left on Phase 1, so if the weather cooperates this week and weekend, and I can get the time to fly off the hours, it should be doable.  I’ll be due for an oil change, too…but that can at least be done in the hangar after dark, whereas the test flight hours need to happen before ~7pm these days…tricky, as it’s just over an hour’s drive from the office to the hangar.

(summary of hours flown since last entry; 7 flights, 15.4 hours)

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1st October 2012

Flight testing notes

A month and a half on, flight testing continues.  As of today, the Hobbs reads 23.00; subtracting the various ground-run time done in pursuit of certification and engine troubles, I have 20.8 flight hours on the plane so far…half done with Phase I operations.

4 days of APRS squiggles, various speeds and altitudes; it’s clear I’m using all of the small test triangle.

Engine break in appears to have gone well, using oil consumption as an indicator; she used or blew out 1/2 quart in the first few hours, then slowly dropped to 7 quarts, where it stayed until I changed the oil this weekend.  On the advice of folks who said that filling it to capacity (8qts) will just dump a quart out the breather, I refilled to 6 qts indicated after the oil change.  7.4 hours of flight time since the oil change, and the level hasn’t budged…still at 6 qts.  Excellent.

Other than the engine stumble/miss, the problems seem to have been sorted out…

  • The cabin CO level seems to have been resolved by the reseating of the #4 exhaust stack, where there was evidence of a small exhaust leak.
  • I did the first oil change at 10 engine hours this weekend, without making too much of a mess.  I also took the opportunity while the sump was empty to remove the quick-drain valve, then clean and reinstall it with better thread sealant — hopefully this will stop a very small weeping leak at the threads.
  • The heavy left wing was out of balance by ~9gal of fuel.  I took another critical look at rigging, and found the left flap was being pulled up tighter than the right; I lowered the left by 1 turn on the rod end bearing, and that brought the imbalance to ~5gal.  Before that, I’d experimented with a small trim tab on the right aileron to see what effect it had…nil.  Today, I taped a larger trim tab (6″ x 3/16″) to the right aileron, and she flew nearly hands-off.  I’ll get some ballast weight to load in the passenger seat, to take the solo-weight imbalance out of play, and see where we are then — if the trim tab is even needed with an even weight distribution.  Once we’re close enough that the roll trim can handle it (Van’s suggests <=3gal imbalance), I’ll pull the seat pans and hook up the roll trim mechanism.

I spent Monday — which I deemed too gusty to fly (at one point something like 19G28 @ 60° from runway heading) — reinstalling the fuel flow transducer.  As part of the engine troubleshooting, the transducer was removed from the FWF area.  Due to mounting considerations, I decided to reinstall it in the center tunnel, under the “doghouse” with the fuel pump.  The law of unintended consequences soon arrived, and I ended up remaking every piece of fuel tubing between the selector valve and the firewall, in order to make everything fit and work.  In the end, though, I believe the install will be more maintainable, since the new configuration makes it easier to get the pump/filter assembly out of the plane.  (I did open and clean the filter while I had it all apart; there was a minor amount of schmutz in there that I attribute to the several thousand paper towels that were used to clean the fuel tanks during the Proseal process…)  Also required with the pluming changes was reflushing the fuel system and a new set of flow tests…I’d estimated the job at 4 hours, but it ended up being 10+ when all said & done.

The nagging problem is the engine stumble/miss.  In addition to removing the 40″ of hose + FF transducer, and replacing it with 29 inches of hose, I also added a heat shield sleeve to the entire fuel servo->spider fuel line.  I’ve not really noticed any difference in operation…it still stumbles/misses (engine folks have said that they use the word stumble for a different symptom) on low RPM operations (final approach & taxi-in, notably) when the engine is warm.  Now that I have a larger body of data behind me from test flights, I’ll call Airflow Performance again to see if they have any additional suggestions–if they think it’s still a boiling fuel issue–and talk to Aerosport Power after that.  I can’t see anything else to do with the fuel system WRT heat loading, other than buy & install the fuel pump cooling shroud that Van’s offers–it couldn’t do any harm, and the pump is definitely hot, but I’ve heard it is a major PITA to install.  Otherwise, we have a forecast cold weekend coming up, which could provide some insight.  (Though, in my opinion, OAT’s in the 60′s and 70′s shouldn’t be causing a problem…)

Flight testing is moving on…in addition to burning up time doing some sightseeing around the test area (leaves are changing fast, and fields being harvested), plenty of actual testing has been done, too:

  • Climb speed tests from 3000′ to 8500′.
  • Glide speed tests on the way back down.
  • Climb to and short cruise at 12,500′.
  • Exploration of power-off stall characteristics: straight ahead, and in increasing banks left & right to 30°.  With flaps up, half, and full.  She’s quite well behaved in all configurations; some exhibit a slight left-wing down tendency, but nothing excessive, extreme, or not easily remedied.  After flying the stall series, I can make it consistently break straight.  The prop-stopped stall from my first flight has never repeated itself, even through the 30+ stall series I did over the weekend.
  • Partial power-on stalls.
  • Exploration of slow flight and MCA regimes with flaps up and down.
  • Tweaks to radio mic gain to improve transmission audio quality.

Since the engine break in is pretty well done, time to start experimentation with LOP operations; initial testing leaning from 75% power, 6.8gph (~50LOP) gives about 145ktas, and 28smpg (better than all of our cars except Allison’s little coupe).  It gets pretty rough beyond that, but I still have the Pmags set in “stock” config, with the low advance curve…rumor says that selecting the higher curve improves LOP operations; we shall see.  CHT’s and oil temps have been great all along; CHT’s on the front cyls are a bit higher than the rears, as expected, but no one is too warm, even on extended climbs.

For fun, today’s test was economy…partial power LOP, at C-150 speeds.  ~90ktas, 2.5gph = 42smpg with over 9 hours endurance.  Even better economy might be out there, with different settings — I just set this up to see what it would do at C-150 speed.  I will also be curious to see what transpires when I get the intersection fairings on, and then have the prop repitched (possibly over the winter, or in the spring months when light & work schedule will conspire to prevent much flying time) to better match the engine & airframe.

I’ve done landings at all of the Phase I area airports now…Red Wing, Boyceville (short & narrow), Menomonie, and Winona.  Winona is a rough airport–the surfaces are deteriorated, and has the highest fuel price (Menomonie is lowest at the moment, followed by Boyceville); I’ve fueled everywhere except Winona.  At Menomonie yesterday, I stopped at the pump, and a fellow building an -8 came over to chat, along with the FBO owner or manager; nice folks, nice airport.  I did 3 landings there tonight before returning to base as the sun set.  I’ve selfishly been timing my return & landing so that I get to see the sunset, and the lights in the towns below coming on, along with the airport beacon & runway lights…it’s a nice sight, though none of my sunset photos so far have done it any justice.  I did get this nifty picture of some farm fields north of Winona in the low sunlight tonight, though…

I have photographed nearly every decent town in the Phase 1 area, along with what seemes like most of the lakes.  More practically, I’ve learned my way around the buttons and menus of the electronic doodads, and don’t have to think much about what to push anymore.  I’ve begun to develop habit patterns for entering flight plans, managing radio frequencies, and so on, along with more mundane stuff like fueling without spilling fuel all over the wing, remembering to sump the tanks, etc.  I’ve developed my mobile office, for days when I still need to deal with emails, server problems, etc, regardless of where I’m at (which is pretty much 7 days a week).  And taken goofy in-flight and on-ground pictures.

19.3 hours left on the Phase 1 clock…

[ summary of shop & flight test hours for the last week was entered on this post ]

Hours: 16.0 | Posted in Flight Test | Comments Off

16th September 2012

More flying

Back out today, I decided I’d run the engine hard for awhile to take care of any break in, though it’s probably finished by now.  Because of all the troubleshooting stuff, there’s been a variety of low-power operation to test various things.  So, off to explore the perimeter of the phase I box.  About an hour’s worth of flying time took me around the edge, from Red Wing down to Winona, up to Menominee, Boyceville, and back home.  Overflights only this time, no landings…keeping the engine at high power.

When she’s up and going, it’s quite nice.  Still stumbling on final & taxi, but nothing noted otherwise.  I burned some fuel out of the left tank to see how heavy the left wing is; the amount of fuel it takes to correct the imbalance is about 9 gal.  A thread on VAF with the math suggested that ~8 gal would be the predicted amount to compensate for lack of passenger weight in a side-by-side RV.  Maybe it’s not that far out after all.  It does require a constant pressure on the stick, though, so I need to sort it out so I can get the roll trim installed.

After refueling, a second quick flight around Lake Pepin before sunset.  The interior lighting works nicely with the dying sun, though obviously I haven’t tried it in actual dark yet.  I need to adjust the wig-wag speed to be slower, as I want the lights alternating on downwind; they don’t need to go steady until on final.  It’s so neat to come into the airport with the field lights on, and to see people’s lights turning on as the sun goes down.

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15th September 2012

Two hops, one hose, zero change.

Off to the hangar this afternoon, armed with parts: a new nozzle line fitting to replace the leaky scratched one, and a 90° -4AN fitting to enable the installation of a shorter servo-to-spider fuel line.  A few hours later, everything was installed and secured.  A test run showed no leaks, so I put the cowling on and went to fly, a quick local flight to get things up to temp and test for changes.  Land, inspect, refuel, and off to fly some more…headed up to Menomonie and back, with a detour to follow a river valley and then up Lake Pepin.

On the up side: the nozzle line fuel leak is, as expected, gone.  Also, the main seal that was weeping a bit of oil seems to have sealed up; there’s no more oil being slung off the ring gear.  And, the EGT drop on #2 seems to have been taken care of by the test & rebuild of the fuel spider.  All 4 cylinders stay together now when pulled to idle.

On the down side, the thing still stumbles as much as it ever did; both subjectively and as shown in the data logs.  I pulled out 40 inches of -4 hose between the servo and spider, and replaced it with 29 inches, which is really about as short as it can be.  The line is routed as far as possible away from exhaust pipes.  I find the hottest place in the line to be the area where it rises up to the purge valve, between the #1 and #3 cylinders.  I was really hoping that the line change would produce some result, even if only a marginal improvement…that’d tell me that we’re on the right track.  The vapor explanation makes sense, given the symptoms and the data logs, but the FI folks seem to think we’re at the end of the road with this, that the hose was going to improve it, and there’s not much more to be done.

A thread popped up on VAF last week that dealt with this same problem, and it’s not unheard of.  Some people seem to accept it and move on.  However, feeling the engine stumble during descent to land and final approach is not confidence-inspiring, and I don’t know that it would cause happy feelings in passengers, either.  Not good, as far as I’m concerned.  Surely there is something that can be done…plenty of folks are running FI without these problems, and it’s not that hot outside right now.

So.  No progress on the biggest issue.  Perfect…I’ll start calling again on Monday and see what “they” want me to do next.  It’ll be two weekends out before I can get back to the problem, since next weekend is stuffed full at work.  (This does make it hard to work with…by the time I’ve been able to test something out on a weekend and report back, the technician has moved on to other problems and I have to reacquaint them with the entire story.)

I also did a ground run with the MP lines disconnected from the Pmags, to get ahead of the question train on ignition problems.  No change.  And, while it was stumbling during the ground run, I alternated ignitions on/off to see if one was different than the other, or causing the problem.  It ran equally lousy on either ignition.  Anything 1200 RPM or above still runs fine.

Hours: 3.0 | Posted in Flight Test | Comments Off

2nd September 2012

Step forward, step back

Headed into the Sunday-Monday “weekend” with high hopes…  one afternoon later, we’re no farther ahead than we were a week ago.

Reinstalled the fuel spider and did a ground run to check operations, then replaced the cowling and went for a test hop.  Something must have been flushed out during all the testing and inspecting, because the EGTs on all four cylinders tracked pretty closely together during the flight.  The hot, low-RPM stumble, however, is just as bad as ever.

Airflow Performance is of the opinion that the stumble is being caused by fuel vaporizing in the lines between the fuel servo and the injectors, most likely in the line from the servo to the purge valve.  They recommended shortening that line as much as possible, and removing the FF transducer for testing purposes.  So, I dug out the original hose that was sent with the engine, and set to work.  It turns out that hose is 2 or  inches too short to run from the servo to the purge valve…it measures 30″ end-to-end, and 32 or 33 would work nicely.

So, having failed on the “short as possible” avenue, I reinstalled the lines I had (which total 40″, split partway through to accommodate the FF transducer), but with the FF removed and a steel union, wrapped with ceramic felt & silicone tape, in its place.  A second test hop revealed that the stumble is still there in this configuration, so the removal of the FF did not help.  The stumble may have been reduced in severity — or it may have just been my wishful perception.  In either case, it is still present.  I suppose the final test would be to procure a shorter hose of the appropriate length to install and test.  The hottest-to-touch part of the hose is the vertical run where it heads up between the cylinders; there’s nothing else to be done there, though.

And, to top it all off, I found that I now have a fuel leak at the spider.  It appears that the nipple line fitting out of the spider for the #3 cyl somehow got a scratch across the seating face.  So I’ll have to order a new one of those, too.

Essentially, that means we’re back on the ground for another week and a half — at least — while I wait for more parts to arrive, family obligations requiring out-of-town travel for a weekend to pass, and evening work commitments to pause.

I’d expected to be at least half done with the test flight hours by now, given that I had a couple weekends with nothing else to do; as it is, I haven’t been out of sight of the airport, and the only flying I’ve done has been to test changes and modifications which have proven fruitless.  There were some disheartening, throw-it-all-away moments during the build; the feeling I have after all this testing (that has only created more problems, solving none) is that, times three.

Hours: 3.0 | Posted in Flight Test | Comments Off

28th August 2012

Analysis, no diagnosis

The fuel spider/purge valve assembly arrived at Airflow Performance this morning, and by early afternoon I had a phone call with the results.  They flow tested it and found it met the specifications.  To be thorough, they disassembled it for inspection, checked over all the internal parts, finding nothing wrong, cleaned & reassembled it.  A second flow test also showed everything to be within new limits, so it’s being sent back to me, hopefully to arrive before the weekend.

Talking with the Airflow folks for a good half-hour (plus the 20 minutes last week), they feel that the colder EGT is of no consequence, and as long as the engine is running smoothly, can be safely disregarded.  We seem to have tied it to fuel flow though, whether due to the spider port or the injector line.

Setting aside that problem for a moment; it is their belief that the hot, low-RPM stumble is related to fuel vaporizing in the line between servo and spider, due to heat absorption and the fact that the fuel in that line at idle is very low volume (<1gph) and pressure (essentially 0 psi, since the flow is so low).  We verified that I have the correct (.022 for the IO-320) restrictors installed.  He said that they get regular calls in the summer months with similar symptoms, and the call volume dries up in the colder months of the year.  Some suggestions were offered for remounting the fuel flow transducer and shortening the servo->spider fuel line as much as possible to minimize heat absorption.

So, the current test plan…

  • reinstall the purge/spider assembly
  • ground run to verify proper operation
  • flight test, observe EGT’s and hot stumble
  • bypass FF transducer with union & firesleeve (or a different hose), see if hot stumble remains and/or improves
  • shorten FWF fuel lines as much as possible/remount transducer in cooler loc’n if testing shows benefit

We’ll see if the forecast holds for Labor Day, which currently is expected to be the crummiest weather of the weekend — guaranteed, since that’s my day off this week…

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