N776R — G3X log review27 Sep 2026

This pass

11 flights from 10 Sep – 27 Sep: the airspeed-calibration test card on 11 Sep, a morning of five circuits at KCLW on 19 Sep, a round trip to Leesburg on 26 Sep, and short local flights. Every figure on this page is now computed by a script from the raw logs, and every qualitative sentence is checked against the data before the page can be built. That checking is what found both retractions below.

1. ReopenedLow fuel pressure at hot idle — §3 On 8 Sep I closed this as a one-off from 4 Sep. It isn't one: 14 of 101 flights dip below 1.5 psi on the ground, back to 15 Feb 2026, and more often on hot days. It happened again on 26 Sep (0.6 psi) and on 27 Sep's ground run after a hot restart (0.4 psi). This is a question for Ray, not a squawk.
2. Retracted"The right sender changed at the annual" — §2 That comparison used an unusually quiet late-August window as its baseline. The right channel read just as noisy in June, July and early August. What the data does support is a right-over-left asymmetry that began right after the June layup, the same point where the CHT #4 fault began.
3. Retracted"The 4 Sep idle fuel-pressure dip was new" — §3 11 earlier flights had the same dip, several of them deeper.
4. HoldingCHT #4 probe, oil temperature, cylinder 3 — §4–§6 All three stay closed. The new flights add nothing against any of them.
5. Unchanged2000–2250 RPM band — §9 Oversquare time is still down 17× since 30 Jul. Time in the 2000–2250 band hasn't come down, and this pass, pattern work added 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. Limits are from the Lycoming O-360 operator's manual (60297-25) in the aircraft folder. N776R has a Superior O-360-EXP, so whether these limits apply is open and belongs with Superior or Pinnacle. They are used here as a screen, not as an airworthiness determination: CHT 500 °F max (435 °F advised for service life; 450 °F is the G3X caution used throughout), oil 245 °F max, oil pressure 60–90 psi normal and 15 psi at idle, carburetor inlet fuel pressure 0.5 psi minimum, 2,700 rpm rated.

One ground run did cross a limit: 27 Sep, the second Young Aviators attempt. The engine was restarted about ten minutes after a hot shutdown and spent 13 minutes on the ground at 31 °C. A minute after start, fuel pressure sagged to 0.4 psi for 9 seconds, just under the 0.5 psi manual minimum, then stepped back to 5–6 psi. That's the §3 hot-idle signature. Oil reached 219 °F, inside the 245 °F limit but hot for the ground, and CHTs reached 431 °F with no cooling airflow. Idle oil pressure fell to 25 psi. That's what this engine reads at that oil temperature: other logs at the same temperature (compared in 2 °F bins, adjusted to 1,000 rpm) read the same. So the low pressure is hot, thin oil, not a pump fault. The takeoff roll was then aborted at 37 kt as a precaution. The day's first flight, which felt down on power, shows normal full-throttle MAP (0.4" below ambient), rpm, fuel flow and EGT balance, and 20–50 kt acceleration of 5.67 kt/s against a 5.77 median at similar density altitude. The G3X doesn't measure oil quantity, weight or humidity.

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. This pass supplied five, and the answer is neither of the two outcomes I set up. The new flights read 1.27% (6,307 samples; 0.17–6.48% by flight, and 11 Sep alone supplies 57% of the samples; 1.61% without it). That is between the two figures I compared.

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 1.99% (37,174 samples) while the left has logged 2 deviations in 19,775. 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 14 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 carburetor-inlet minimum in the manual. 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.

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

17 flights since the probe change, 0 episodes, 6,247 warm-idle seconds with 0 flagged. The deepest dip at idle on any of them is +4 °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 50 flights since 3 Jul. Peaks run 182–215 °F, inside the ordinary range and far from the 245 °F limit. The vernatherm passed its bath test at the annual.

One change to how the residual is measured. The first cut of this 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 4.6 °F. The residual is now reported only for flights with at least 10 minutes of cruise (55 flights; 41 excluded). On those, the new flights read +1.4 to +6.1 °F. On 19 Sep the peaks rose leg over leg, 182 → 190 → 208 → 204 → 215 °F, as heat built across back-to-back circuits with short stops. That's normal, and it's still under the ordinary maximum.

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 all 17 of 17 flights, because it heats fastest in the climb. In level cruise the hottest cylinder was #1 on 5, #3 on 2 and #4 on 9 of 16 flights. Spread runs 7–27 °F and peaks 377–438 °F. Which cylinder tops the list is a matter of a few degrees and shifts with altitude and power.

7RPM

No flight this pass went above 2,800. The highest was 2,780. Across all 101 flights, 87 touch 2,700 and 45 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 −4.3 rpm per 25 h, r = -0.12: no trend.

8Clean over 78.5 engine hours

Oil pressure is the one line that moved, and the oil change explains it. Normalized to 190 °F and 2,380 rpm, it was flat for 80 flights up to the annual and has sat +2.1 psi higher on the 16 since. The annual put in fresh 20W50. Fitted across the whole dataset, that step would read as an upward trend of +0.58 psi per 25 h at r = 0.45. It isn't wear, it's the oil, and higher pressure is the benign direction anyway.

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: 88.8 h running and 64.2 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 7.08%, each with its largest flight removed (20 Aug: 2,196 s on one leg). Across everything, 58% of band time is level flight and 60% is below 1,500 ft. This pass put 10.2% of running time in the band, and 45% of that was below 1,500 ft: circuit work on 19 and 27 Sep, plus the low-power legs of the test card. 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

91 stabilized cruise segments, 5.7 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 (43 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. A deliberate mixture sweep at a fixed altitude and power would say whether the four cylinders peak close enough together for lean-of-peak to be an option at all.

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 a Superior O-360-EXP, 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

Twelve measurements have now been walked back. The two added this pass rhyme with the earlier ten.

Both new 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.