N776R — G3X log review20 Oct 2026

This pass

7 flights, 16 Oct – 20 Oct. On 16 Oct Steven and Emily flew home from Gatlinburg–Pigeon Forge by way of Heart of Georgia (Eastman) and Tampa Executive. On 19 Oct he flew solo crosswind practice at KCLW (one go-around, one full stop). On 20 Oct he flew solo from KCLW to Oshkosh, stopping at Thomson–McDuffie, GA and Highland County, OH. The 5 long legs cruised at 7,200–9,400 ft, in air down to 11 °C, and they were leaned with the lean assist, as on 13 Oct. That adds 5 long, ordinary cruises to the 2 that §8 had after Bender. Nothing crossed a limit.

1. Still openOil pressure is holding below its pre-annual level — §8 All 7 long legs since Bender read 67.4–68.8 psi normalized. All 5 pre-annual flights at the same cruise oil temperature read higher (lowest 69.5). 20 Oct's 67.4 is a new low, 0.2 psi under 4 Oct's. That's well inside the 0.7 psi flight-to-flight scatter, and the post-Bender trend is flat. Both of the watcher's WATCHes this pass are the same level seen with cold oil. 20 Oct's runup read 72 psi at 2,096 rpm and 134 °F oil, −4.9 psi from 11 pre-Bender runups at that oil temperature. Idle sat as much as 3.9 psi under the pre-Bender median at the same oil temperature. Every reading is inside the limits, and the question for Bender and Ray stands.
2. Corrected"Which cylinder peaks depends on how long and how high the climb is" — §6 13 Oct's explanation didn't survive the next flights. On 16 Oct's short leg home, cruising at 952 ft, #3 tied #4. Two high legs went to another cylinder by 1 °F. Which cylinder tops the list is a matter of a degree or two, and the rank carries no cause.
3. Not a squawkCylinder 4 runs coolest in high cruise — §6 The cruise spread reached 34 °F on 20 Oct, at 8,100 ft, the widest since the fix. EGT agrees with CHT: #4 had the coolest EGT on all 10 post-fix legs above 6,000 ft. That looks like mixture distribution, not a probe. It's the cool side, and the warmest cruise cylinder stayed at 366 °F.
4. Still openLow fuel pressure at hot idle — §3 One dip this pass: 0.7 psi for three seconds, leaving Tampa Executive on a 31 °C afternoon, above the 0.5 psi minimum. The question for Ray stands.
5. HoldingOil temperature, right-sender noise, CHT #4 probe — §2, §4, §5 Ordinary cruise residuals of +1.9 to +6.3 °F, sender noise inside its logged range, and no #4 episodes. The new flights add nothing against any of them.
6. Unchanged2000–2250 RPM band — §9 Oversquare time is still down 13× since 30 Jul. Time in the 2000–2250 band hasn't come down, and this pass added 1,103 s to it.

A data-source note. Twelve logs from 29 May to 25 Jul went missing from the Drive log folder during the September re-filing. They were restored on 27 Sep from the 11 Sep SD-card archive (log_20260911_N776R.zip), byte-identical, and the folder is complete again.

1Standing limits screen

The check the 8 Sep pass admitted it had never built, now run on every flight. Since 14 Oct the limits are Superior's, from the Model Specification Data in the O & IO-360 Installation & Operation Manual (SVIOM01, Appendix A, Feb 2007). Until then the screen used the Lycoming O-360 operator's manual (60297-25). Ray says the engine is a Superior O-360, and the paperwork says O-360-EXP. The data plate hasn't been photographed yet, so which Superior model it is remains open. The limits are a screen, not an airworthiness determination:

• Oil pressure 55–95 psi normal, 20 psi minimum at idle, 115 psi maximum cold (Table 5). Chapter 6's run-up caution says 50–95, and the table is used here. Was 60–90 / 15 / 100.
• Oil temperature 240 °F maximum and 75 °F minimum for takeoff (Table 9). 130–200 °F is recommended in cruise. Was 245.
• Fuel pressure 0.5–8 psi (Table 3). Superior states this at the inlet of the engine-driven pump. The G3X sender on a carbureted RV-6 usually sits after that pump, at the carburetor, so the 0.5 psi floor isn't measured at the same point.
• CHT 500 °F maximum (Table 11). For service life, below 430 °F in high-performance cruise and below 400 °F in economy cruise (Table 6-7). 450 °F is the G3X caution, used throughout. Was 435 advised, counted on any airborne second. 430 is now counted in level cruise only, as Superior states it.
• RPM 2,700 rated, unchanged.

The whole record against Superior's limits (114 flights since 7 Feb): oil at most 230 °F (3 Jul's excursion, §5), oil pressure at power never below 62 psi, at idle in flight never below 31 and at ground idle never below 22 (29 Jun, against the 20 psi minimum), at most 93 psi cold and 88 warm, oil never below 115 °F at takeoff, and fuel pressure at most 7.8 psi, close to the 8 psi maximum, probably with the boost pump on (the log has no boost-pump channel). The switch creates no new limit crossing anywhere in the record. No flight has had level-cruise CHT above 430 °F (outside the first three minutes after liftoff). 4 had a minute or more of cruise above Superior's 400 °F economy-cruise figure, the last on 24 May. That figure applies at economy power, and the screen can't tell economy from high-performance cruise, so it is a NOTE only.

The 27 Sep ground run (after a hot restart) is still the only log since 8 Sep to cross a limit: fuel pressure fell to 0.4 psi, just under the 0.5 psi minimum. That's the §3 hot-idle signature. That day's first flight, which felt down on power, measured normal on full-throttle MAP, rpm, fuel flow, EGT balance and takeoff acceleration.

2Fuel senders — the step change retracted, a layup onset in its place

On 8 Sep I reported that the right sender's noise had stepped up across the annual: 0.71% at 6–12 gal in late August against 2.77% on 5–7 Sep, "ratio 3.9×, z = 6.6". The test was three or four more flights in that band. The 27 Sep pass supplied five, and they landed between the two figures I compared, which was neither outcome I had set up. The 7 flights this pass with enough samples in the band read 0.35% (18,573 samples, 0.0–2.7% by flight), at or below the 1.51% logged since 29 Jun. Each flight sits inside the per-flight range over that time (up to 12.30%).

What the level-controlled comparison does show is a clear change at a different point. Before the June layup, both channels behaved alike: right 0.50%, left 0.81% (24,420 and 18,123 samples). From the first flight after it, the right has read 1.51% (62,739 samples) while the left has logged 9 deviations in 36,484. The left gauge is not simply stuck: it falls 5–6 gal on flights that draw from the left tank, in line with integrated fuel flow. G3X software is 9.33 in every log, so a software change doesn't explain it.

Watch item, not a squawk, with a narrower question. A 1–3% flicker rate means the right gauge occasionally jumps 2 gal or more for a moment. That's an annoyance at mid-tank, not a hazard, and nothing suggests it is getting worse. The useful observation is the timing. The right channel's change and the CHT #4 fault both begin on the first flight after the month-long June layup. Two unrelated sensors changing at the same moment is worth one question to Ray: was anything done behind the panel, to the EIS or sender wiring, or to the fuel-quantity calibration during the June layup? That is a hypothesis, not a finding. The CHT #4 fault was cured by replacing the probe, which argues against a shared cause.

3Low fuel pressure at hot idle — reopened

On 8 Sep I wrote that 4 Sep's 0.9 psi taxi dip stood "against 2.0–3.5 psi on every prior flight", and closed it when five flights passed without a repeat. Both halves were wrong. Scanning every flight with the same statistic, the minimum taxi fuel pressure, finds 15 flights with readings below 1.5 psi. 11 of them predate the annual, going back to 15 Feb 2026, and 3 went below the 0.5 psi minimum. Superior states that minimum at the engine-driven pump's inlet, upstream of where this sender most likely reads. On 26 Sep, departing Leesburg after about two hours on the ramp, it spent 44 seconds below 1.5 psi, bottoming at 0.6. The next evening's ground run after a hot restart went to 0.4 psi. This pass had one. On 16 Oct, leaving Tampa Executive, the reading touched 0.7 psi for three seconds at about 1,260 rpm, 78 seconds before liftoff. KVDF reported 31 °C at the time; the G3X probe read 36, heat-soaked on the ramp. It had sat three hours on the ramp since landing, much like 26 Sep at Leesburg. There was no runup before that leg, so the boost pump may not have been on yet. The log can't say.

Re-binned 21 Oct by airport temperature. Until this pass the table used the G3X's own OAT, which heat-soaks on the ground. Against the airport reports it read a median 2.7 °C high (middle half 1.8–3.9, up to 7.0; 111 flights), and a little more on the hottest days (3.7 °C at 31 °C and above), so the old top band held cooler days than its label said. The finding holds, and it's sharper: 40% of departures at 31 °C and above had a dip, against 9% at everything cooler.

The shape is consistent, and it points at the boost pump. On 26 Sep and on 25 May (the deepest recent case, 0.1 psi), fuel pressure reads 5–6 psi just after start, sags to 0.5–1 psi over the next one to two minutes at idle, then steps back up by 2.2–2.5 psi at constant rpm about four minutes before takeoff. The checklist has the boost pump on for start, off for taxi, and on again for runup and takeoff. The log has no boost-pump channel, so this is inferred, not measured: the dips look like the engine-driven pump alone at hot idle. Rpm and fuel flow stayed steady through every dip, and nothing starved.

4CHT #4 probe — fixed, and staying fixed

30 flights since the probe change, 0 episodes, 11,152 warm-idle seconds with 0 flagged. The deepest dip at idle on any of them is +1 °F, so the channel has never once read below cylinders 1–3 while idling. Before the change, the last six flights flagged 39% of idle time. Counting each 60-second idle block as one independent trial, which is deliberately conservative, the chance of this clean a run from the old probe is below 10⁻²⁰.

5Oil temperature — closed, and a method fix

No excursion in 63 flights since 3 Jul. Peaks run 182–215 °F, inside the ordinary range and far from Superior's 240 °F limit. The vernatherm passed its bath test at the annual.

One change to how the residual is measured. The first cut of the 27 Sep pass showed new-flight residuals of −17 to +14 °F, against the ±6 °F scatter reported before. All of them came from the 19 Sep circuits, where each leg had only four to six minutes of "cruise" and the oil never reached equilibrium. Below 300 s of cruise the residual scatters with a standard deviation of 9.6 °F; above 600 s it's 4.5 °F. The residual is now reported only for flights with at least 10 minutes of cruise (67 flights; 42 excluded).

This pass. All three flights had ordinary level cruise, and they read +1.9 to +6.3 °F, inside the scatter. 4 Oct's formation leg, +9.8 °F, is still the second-highest on the page. Bender found the oil cooler door not opening fully and debris in the cooler's air inlet. Oil temperature never showed the restriction, and it doesn't show the fix either: the median residual is +3.8 °F since Bender, +2.6 °F between the annual and Bender, and +1.1 °F before, against a scatter of 4.5 °F. If the door and the debris cost cooling, it was less than this measurement can resolve.

6Cylinders and CHT

The cylinder-3 squawk stays retracted: a 5 °F lead, a 10 °F spread, and 79/80 compression. After the fix, cylinder 4 holds the in-flight peak on 25 of 30 flights. In level cruise the hottest cylinder was #1 on 12, #3 on 3 and #4 on 14 of 29 flights. Spread runs 6–34 °F and peaks 371–438 °F. Which cylinder tops the list is a matter of a few degrees.

Corrected, 20 Oct: "which cylinder peaks depends on how long and how high the climb is." 13 Oct's explanation, offered below, rested on two legs. The next flights broke it. The exceptions to #4 now number 5: 13 Oct 06:53 #1 404 °F against #4's 404 at 9400 ft cruise; 13 Oct 11:59 #1 371 °F against #4's 361 at 8300 ft cruise; 16 Oct 10:04 #3 436 °F against #4's 435 at 7300 ft cruise; 16 Oct 15:00 #3 424 °F against #4's 424 at 1000 ft cruise; 20 Oct 15:16 #2 408 °F against #4's 407 at 8100 ft cruise. The 16 Oct 15:00 leg was a short, low hop on a hot afternoon, a tie with no long climb in it. The G3X logs whole degrees, so a tie or a 1 °F lead is a coin toss. What the record supports is the magnitude: every exception is within 10 °F, far below any limit.

Cylinder 4 runs coolest in high cruise. On the 19 post-fix flights cruising below 6,000 ft the spread is 6–16 °F. On the 10 above it, 10–34, and #4 is the coolest. It runs 2–34 °F under the mean of #1 and #3, and its EGT runs 21–154 °F under the other three. #4 had the coolest EGT on all 10 of them. The widest spread, 34 °F on 20 Oct at 8,100 ft, read CHT 346/335/347/312 and EGT 1,324/1,301/1,274/1,146. The EGT is the independent witness: a cylinder cool on both channels is getting a richer mixture or less charge, not reading low on one probe. It was already there before the lean assist. The 3 high cruises before 13 Oct had #4's EGT 21–85 °F low and spreads up to 27 °F. Leaning roughly doubles it: on the 7 leaned high cruises since, #4's EGT ran 74–154 °F low. That fits the §10 sweeps, where #4 was among the last to peak: on a carburetor, the richest cylinder sits furthest rich of peak when the first is set 100–150 °F rich. That part is inference. The screen has no limit for spread, and every reading here is on the cool side.

Corrected, 13 Oct: "cylinder 4 holds the in-flight peak on every post-fix flight, because it heats fastest in the climb." Both 13 Oct legs broke it. On the first, #1 and #4 tied at 404 °F (the G3X logs whole degrees, and the tie went to #1). On the second, #1 reached 371 °F against #4's 361 °F. In both logs #4 peaked first, in the opening minute at full power. #1 matched or passed it later, in a climb of eight to thirteen minutes to 8,297–9,359 ft. At altitude #1 runs warmer than #4 (the §4 cruise offset depends on altitude), and a long climb gives it time to get there. Of the 10 post-fix flights that cruised above 6,000 ft, #4 kept the peak on 6, by a few degrees. Neither leg was leaned harder in the climb: their climb fuel flow, per unit of rpm and MAP, was among the richest after the fix. So the "because" was a rank promoted to a rule. Which cylinder peaks depends on how long and how high the climb is (withdrawn 20 Oct, above), and the margin (0 and 10 °F) sits far below any limit.

7RPM

No flight this pass went above 2,800. The highest was 2,790. Across all 114 flights, 98 touch 2,700 and 48 touch 2,750, nearly all in the normal takeoff overshoot. 3 exceed 2,800, and every one of those peaked in a descent with the throttle moving. That's governor lag with the prop unloaded, and the cure is easing the throttle in or letting the speed come back first. Peak rpm against engine hours runs −4.7 rpm per 25 h, r = -0.15: no trend.

8Trends over 97.5 engine hours: oil pressure stepped twice

Withdrawn, 4 Oct: "the oil change explains it." The 27 Sep review said oil pressure rose after the annual because the annual put in fresh 20W50, so the rise wasn't wear. The rise has now reversed with that same oil still in the engine: Bender Aviation didn't change or add oil. A change of oil can't explain a step that undoes itself while the oil stays the same. The cause was assigned because the timing coincided, without a second witness. Holding the oil constant was the test, and the Bender visit ran it by accident.

What was measured. Normalized to 190 °F and 2,380 rpm, for flights with at least 10 minutes of cruise: before the annual, median 69.8 psi (48 flights, 68.1–71.7), and flat across all 80 pre-annual flights with a cruise reading. From the annual to Bender, 72.8 psi (7 flights, 72.0–73.9). Since Bender, 68.2 psi (12 flights, 67.4–69.2). The lowest, 67.4, is the lowest of the 67 flights on this page. It's still inside every limit: the lowest at power this pass was 66 psi, against Superior's 55 psi normal minimum.

Where it has settled. On 4 Oct this was three flights from one hot day, a first look. There are now 7 legs with at least 30 minutes of ordinary level cruise since Bender, averaging 179.5 °F oil. They read 67.4–68.8 psi. All 5 pre-annual flights with cruise oil within 3 °F of that temperature read higher: median 70.3, lowest 69.5. Cruise altitude doesn't explain it: before the annual, flights cruising above 6,000 ft had a median of 70.2 psi (8 flights) and flights below 4,000 ft 69.8 (33). Cold-oil readings agree. 20 Oct's runup read 72 psi at 134 °F, −4.9 psi from the median of 11 pre-Bender runups at that oil temperature, lower than all of them. Ground idle on 20 Oct read 50 psi at 134 °F (adjusted to 1,000 rpm), −3.9 from the pre-Bender median there. So the post-Bender level is real: about 1.6 psi under the pre-annual median, across 12 flights, hot days and cold.

Is it drifting? Not on this evidence. The lowest reading is now 20 Oct's 67.4, 0.2 psi under 4 Oct's 67.6. Before the annual, flight-to-flight scatter was 0.7 psi (one standard deviation). That leg had the coldest cruise oil since Bender, 172 °F, so the first suspect was the normalization. It isn't that: across 48 pre-annual flights cruising at 173–221 °F oil, the normalized figure moves −0.006 psi per °F, which is no bias. Over the 16 days since Bender the fitted slope is −0.018 psi a day, and 4 Oct's first flight (69.2) carries all of it. Without that flight the slope is +0.005. That's flat. Sixteen days can't rule out a slow drift, and the automatic block will show it if one starts. One thing the G3X can't see: Steven added a quart of oil at KHOC before that leg. Oil quantity is not a channel, so whether the top-up moved the reading at all is open.

What the record can't say. Both steps line up with time in a shop: up at the 4 Sep annual, down across Bender's 28 Sep – 4 Oct visit. The debris was on the cooling-air side (the cooler's air inlet and the cylinder fins). Because this comparison already holds oil temperature constant, a blocked air inlet on its own shouldn't move pressure at a given oil temperature. That is inference, not measurement. The timing doesn't fit the FOD either: the rise was already there on 5 Sep (72.4 psi or more), flying home from the annual at Kaolin, before the airplane was back at KCLW. The G3X has no channel for oil quantity, oil grade or relief-valve position, and it can't tell a real pressure change from an offset in the sender. The question for Bender and Ray: at the annual or at Bender, was the relief valve removed, reshimmed or adjusted, or the oil-pressure sender or its wiring disturbed? That decides it, not the telemetry.

9Propeller placard bands

The Hartzell HC-C2YR-1BFP / F7497 manual carries two placard blocks, for an ECI (I)OX-360 and a Lycoming O-360-A1A with Lightspeed ignition. Neither is N776R's engine, and whether either applies is open with Hartzell and Pinnacle. What the logs can do is measure exposure: 108.4 h running and 81.3 h airborne across the flight set.

The 2000–2250 band has not come down, and it is now the larger exposure. Before 30 Jul it was 5.59% of running time and after it 5.74%, each with its largest flight removed (20 Aug: 2,196 s on one leg). Across everything, 58% of band time is level flight and 58% is below 1,500 ft. This pass put 2.4% of running time in the band, and 55% of that was below 1,500 ft. The largest share (301 of 1,103 s) came on 19 Oct's 13:17 flight. Unlike the oversquare band, no technique change has touched this one. If the Lycoming placard ever turns out to apply, this is the live item, and setting low-power cruise and downwind at about 2,300 rpm would clear it at little cost.

10Performance charts

156 stabilized cruise segments, 9.8 hours with rpm steady within 60, MAP within 0.8", airspeed within 4 kt and vertical speed under 100 fpm for at least two minutes. They cover 1,253–9,428 ft and 36–70% power. The 11 Sep test card added the low-power points. That card also validated the airspeed system: position error is +0.7 kt, constant within ±1 kt from 80 to 145 KIAS, and the logged OAT is static temperature. So every TAS figure here is good to about a knot.

Specific range runs 13.7–20.8 nm/gal. At 7,000–8,200 ft (91 segments) the best segment made 168.3 kt on 8.1 gph and the worst 159.5 kt on 11.18 gph: 5% slower for 38% more fuel. On 31 usable gallons (36 indicated less a 5 gal reserve; confirm against the build documentation) that is 645 nm against 425 nm of still-air range. None of this recommends leaning differently. Mixture is Superior's guidance and your call; the data just puts a price on the choice.

The first mixture sweeps, 13 Oct. Steven used the G3X lean assist on both legs: lean to peak EGT, then enrich, aiming for every cylinder 100–150 °F rich of peak. The second sweep (KOKZ–KGKT, 8,290 ft, 19.6") took all 4 cylinders to a confirmed peak, and the setting he chose, 8.9 gph, put them 105–160 °F rich of peak: #1 105, #2 160, #3 120, #4 150. On the first (7,370 ft, 22.2") the mixture came back in while #2 and #4 were still rising. #1 and #3 settled 115 and 120 °F rich of peak, and #2 and #4 at least 185 and 190. That's richer than intended, which is the cool side. The lean assist tracks the first cylinder to peak, so on a carbureted engine the others land further rich. The fuel flow at which each cylinder peaked spread 0.3 gph on the second sweep. On the first, #2 and #4 had still not peaked about 0.8 gph below #1's peak. Both sweeps were fast (one to two gph every ten seconds), and the probes lag. So these spreads are approximate, and they may differ with throttle position, since the first was at 22.2" and the second at 19.6".

Superior's leaning guidance. The 4 Oct page asked whether the cylinders peak close enough together for lean-of-peak to be an option. Superior's manual (SVIOM01, Chapter 6 and Appendix A) settles that for this engine, and says where to run instead:

What the curves show. CHT peaks about 30–60 °F rich of peak EGT. At the maximum-power mixture it runs about 10–25 °F below that peak. At peak EGT it runs close to its peak for that power, which is why Superior pairs economy cruise with the 400 °F figure. At 65% power, going from maximum-power mixture to peak EGT saves about a quarter of the fuel for about a fifth of the power, roughly 7–8% of airspeed. Those figures are read from the curves for Superior's test engine, so treat them as approximate.

Where 13 Oct sat. By the G3X's own estimate the cruise was 61% and 58% power, so economy-cruise territory. Steven's target, 100–150 °F rich of peak, is Superior's maximum-power mixture. It's valid at any cruise power up to about 80%, and peak EGT is the economy alternative at these powers. Both are inside the manual, and which one to fly is the pilot's call. One thing the sweeps add: lean assist references the first cylinder to peak, and on this carburetor #2 and #4 run richer. With the first cylinder 100–150 °F rich of peak, the others sit further rich: at least 185 and 190 °F on the first sweep. On Superior's 65% curve that costs about 2% of power, and it's the cool side. Setting the first cylinder nearer 100 than 150 keeps all four closer to maximum power. For peak-EGT economy, the first cylinder to peak is the conservative reference: the others then stay rich of their own peaks, which is what "not below peak" requires. None of this is specific to N776R's installation. The RV-6 has no engine-specific handbook, and Ray is the one to ask about this airplane.

What it did to the CHTs. 13 Oct ran the warmest post-fix cruise CHTs on #1 and #3, 366 and 363 °F (the warmest on any cylinder is still 4 Sep's 367 °F on #4, low and hot, the day of the annual). On the first leg two things changed together, so the log can't separate them: the throttle was further open at altitude than on earlier high cruises, and the mixture was set by the sweep. The second leg is cleaner. Its throttle and altitude were close to 5 Sep's trip home from Kaolin, and it cruised warmer on less fuel, with higher EGTs on #1–#3. That's the mixture. Every cruise reading stayed below Superior's 400 °F economy-cruise guidance.

11Marking it in the cockpit — carried forward

Unchanged from 8 Sep. The 2000–2250 band and the 2,600 takeoff-only limit can be expressed as tach arcs or G3X alerts. The oversquare rule relates two instruments, so no arc can express it, and it needs a placard. Until Hartzell says whether these placards bind N776R's Superior O-360, the honest sequence is an advisory placard on the quadrant plus a G3X checklist page now, with arcs and alerts only after the answer.

12Retractions, and the pattern

Fifteen findings have now been walked back. This pass's is the cause offered on 13 Oct, to replace the rule withdrawn that day: an explanation fitted to two exceptions, broken by the next three. 4 Oct's was also a cause: the oil-pressure step was real, and its explanation failed.

The 27 Sep pass's two failures came from the same gap. A number from recent flights was compared against a convenient slice instead of the whole record. The fix is structural, not a matter of care: the script now computes every figure over every flight with one definition, and states each claim as a test it must pass before the page can be built. 4 Oct's withdrawal was checklist item 7: a step that coincided with a maintenance event was credited to one thing done at that event, with no independent witness. 13 Oct's was item 4 again, rank without magnitude, and its replacement explanation was item 5: two cases carrying a rule. The claim test caught both the first time the data moved. The magnitude was the finding all along: every exception is within a few degrees.