Skip to content

Phase0-USB-Inspection-Findings.md

Latest commit

 

History

History
420 lines (327 loc) · 22.3 KB

Phase0-USB-Inspection-Findings.md

File metadata and controls

420 lines (327 loc) · 22.3 KB
Raw

Phase 0 — USB Drive Inspection Findings

Drive: /Volumes/EFIS — 30 GB FAT32, 18 GB used, 12 GB free
Aircraft: N488BF (from Settings.bak field 1062)
Date of inspection: August 2026

1. Top-Level Drive Structure

/Volumes/EFIS/
├── DEMO-YYYYMMDD-HHMMSS.LOG        # Demo recording sessions (base file)
├── DEMO-YYYYMMDD-HHMMSS+N.LOG      # Continuation files for same session
├── Settings.bak                      # EFIS settings backup (key=value text, checksummed)
├── State.bak                         # EFIS state snapshot (key=value text, checksummed)
├── WP.bak                            # Waypoint backup
├── Plan.bak                          # Flight plan backup (lat/lon waypoints with names)
├── HHXRUp-proc.dat                   # EFIS firmware update file (7.6 MB)
├── NAV-proc.DB                       # Nav database "processed" (9.9 MB)
├── NAV.DB                            # Nav database (7.9 MB)
├── SNAP####.PNG                       # Pilot-saved screenshots (manual save from EFIS)
├── GRTCHARTS/                        # GRT chart marker directory (required flag, contents disposable)
│   └── E:GRTCHARTS/                  # Empty directory (Windows artifact, safe to remove)
├── ChartData/                        # Seattle Avionics chart data (~17 GB)
│   ├── ScannedCharts.sqlite          # Chart metadata DB (cycle, expiry, URLs, passwords)
│   ├── LO/                           # IFR Low Altitude chart tiles (~1.0 GB)
│   │   └── W062..W180/              # Longitude-based tile directories
│   ├── SEC/                          # VFR Sectional chart tiles (~3.8 GB)
│   │   └── W060..W180/
│   ├── Plates/                       # Approach plates/airport diagrams (~3.6 GB)
│   │   ├── Plates.sqlite            # Plate index DB (airports, charts, geo-ref)
│   │   ├── Plates.sqlite.chk
│   │   ├── Airports.txt, Charts.txt, Cities.txt, Plates.txt, States.txt, Plates.xml
│   │   ├── US/                       # US plate images (PNG)
│   │   ├── MG/, MH/, MM/, MN/, MR/, MS/, MZ/  # Mexico/other region subdirs
│   │   └── (no FG/ directory present)
│   └── E:ChartData/                  # Duplicate/alternate structure (~8.4 GB)
│       ├── ScannedCharts.sqlite
│       ├── LO/, SEC/, Plates/       # Same structure as parent
│       └── (appears to be an older or backup copy)
└── System Volume Information/        # Windows system folder (FAT32 artifact)

2. DEMO File Convention (Engine Telemetry)

Naming Pattern

DEMO-{YYYYMMDD}-{HHMMSS}.LOG          # Base file for a recording session
DEMO-{YYYYMMDD}-{HHMMSS}+{N}.LOG      # Continuation file N (1-based)
  • Date/time in filename = recording start time (local time, based on EFIS clock)
  • Base file (no +N) is always smaller (~270-310 KB) — contains full settings dump as header
  • Continuation files are capped at ~6 MB each (6,291,000–6,294,000 bytes typical)
  • Final continuation file in a session is typically smaller (partial fill)

Session Summary (29 sessions on drive)

Date Files Est. Duration Notes
2025-11-12 16 (base + 15) ~1.5 hr First session on drive
2026-02-15 17 (base + 16) ~1.5 hr
2026-03-07 5 ~30 min
2026-03-13 2 sessions (1 + 18 files) short + ~1.5 hr
2026-03-15 22 ~2 hr Longest session
2026-03-21 13 ~1 hr
2026-03-26 3 sessions (4+11+6) Multiple flights
2026-03-27 6 sessions (2+3+11+10+3+16) Multiple flights Busy day
2026-03-28 5 sessions (1+3+13+2+4) Multiple flights
2026-04-24 9 ~45 min
2026-05-24 2 sessions (1+1) Very short
2026-05-30 1 Very short
2026-06-06 3 sessions (1+7+9) ~1 hr total Most recent

Total: 210 files, ~2.1 GB

Binary Format Analysis

The DEMO file is a binary record stream, not a flat binary blob. Record structure observed:

Record header: {type:1}{unknown:2}{seq_id:2}{flags:3}{payload_len:1}{payload:N}

  • Type 0x07 — Settings/configuration (key=value ASCII strings)

    • These appear at the beginning of every file (base and continuation)
    • Contain the full EFIS Settings.bak content embedded in record format
    • The seq_id field increments (e.g., 0x0d6c, 0x0d6d, ...)

  • Type 0x02 — Engine data packet (packed binary)

    • Appears after GPS sentences
    • Contains multi-byte packed values for engine parameters
    • Example decoded (tentative): 49 feff fe 05 42 00 fd 01 11 01 15 01 0f 00 55 00 59 04 c7 04 bc 04 cc 04 dd 00 53 00 92...
    • Pattern suggests: RPM(2) + multiple 2-byte channel values (CHT×4, EGT×4, oil, fuel, etc.)

  • Type 0x09 — Short data records (5-byte payload typical)

    • Appear frequently between other record types
    • Likely individual sensor updates or status frames

  • Type 0x13 — Longer records (often 19-20 bytes)

    • Contains 7e6a8d pattern (appears to be a marker/signature)
    • Possibly encrypted/compressed AHRS data or multi-sensor fusion

  • Type 0x0b/0x14 — Variable-length records containing NMEA GPS sentences

  • Type 0x04 — Short (36-byte) records, possibly display/status updates

  • Type 0x01 — Variable records (often contain 7ffffe or 7ffffd patterns)

    • Likely AHRS/attitude data (pitch, roll, heading, airspeed, altitude)

GPS Data Confirmed Present

NMEA sentences embedded in the data stream:

  • $GPGGA — Fix data: lat, lon, altitude (MSL), fix quality, HDOP
  • $GPRMC — Position, speed, course, date
  • $GPGSA — DOP and active satellites
  • $GPGSV — Satellites in view

Example from data:

$GPGGA,172609.000,3318.8278,N,08446.4126,W,2,9,0.91,304.2,M,-30.3,M,0000,0000*6C
$GPRMC,172609.000,A,3318.8278,N,08446.4126,W,0.00,0.00,211006,,,D*75
$GPGSA,A,3,21,29,11,20,05,25,12,18,15,,,,1.27,0.91,0.88*08

This confirms: lat/lon, GPS altitude, ground speed, ground track, and date/time are all available in every demo file. Route reconstruction is feasible.

3. Logbook Data — Not on Drive (Manual Save Required)

Finding: No logbook CSV is currently present on this USB drive. This is expected — the GRT HXr requires the pilot to manually trigger a logbook save from the EFIS menu. When saved, it produces a full-history CSV file (e.g., Logbook 2025-01-15.csv).

Implication for FR-4.1: The logbook CSV is a complete dump of all flight history each time it's saved (not incremental). It contains structured flight records with origin, destination, times, fuel used, hourmeter, and oil-added fields. See Section 7 below for full format analysis.

Dual-source approach for flight records:

  • Primary: Logbook CSV when available (complete, structured, includes fuel data)
  • Supplemental: DEMO file sessions can fill gaps between logbook saves (derive flight start/end from filename timestamps + GPS position for airports)

4. Chart Data Structure

Key Architecture Insight

The EFIS reads chart data from /ChartData/ at the root of the USB/SD card. The directory structure is:

  • /ChartData/ScannedCharts.sqlite — Master database with RegionalExpDates table containing cycle info, passwords, download URLs for all chart types. Also has an Info table with overall cycle/version data. Current cycle on drive: 2411 (Oct-Dec 2024) — significantly outdated.
  • /ChartData/LO/W{nnn}/ — IFR Low chart tiles organized by west longitude
  • /ChartData/SEC/W{nnn}/ — VFR Sectional tiles, same scheme
  • /ChartData/Plates/ — Approach plates with SQLite index
  • /ChartData/Plates/US/ — US plate PNGs (~146,975 files total across all chart dirs)

E:ChartData Mystery

The E:ChartData subdirectory inside /ChartData/ appears to be a duplicate left behind by the Windows-based ChartData Manager when it was last used. It references the Windows drive letter (E:) that the SD card was mounted as. It contains the same structure (LO, SEC, Plates, ScannedCharts.sqlite) but is ~8.4 GB — less than the full 17 GB, suggesting it may be a partial/older copy.

Decision needed: Should our automation preserve E:ChartData, remove it (reclaiming ~8.4 GB), or ignore it? The EFIS likely reads from the root /ChartData/ path, not the E: prefixed one.

SQLite Metadata (FR-2.13 Opportunity)

ScannedCharts.sqlite contains RegionalExpDates with columns: Region, Subregion, FileType, ExpDate, Cycle, Pwd, URL, FriendlyName, TMSTilesURL, MBTilesURL, StartDate, UserSelected.

Plates.sqlite Info table shows: Version=1, Start_Date=2026-05-14, End_Date=2026-06-10 — plates are cycle 2606, much newer than the scanned charts (cycle 2411). This suggests charts were partially updated at some point.

5. EFIS System Files

File Size Purpose
HHXRUp-proc.dat 7.6 MB EFIS firmware/software update file (processed format)
NAV-proc.DB 9.9 MB Navigation database (processed for EFIS)
NAV.DB 7.9 MB Navigation database (source/raw)
Settings.bak 8.4 KB Full EFIS settings dump
State.bak 800 B Current EFIS state
WP.bak 52 B User waypoints
Plan.bak 1.6 KB Flight plans (ICAO idents + lat/lon)

Settings.bak notable fields:

  • 1062=N488BF — Tail number
  • 1063=A60670 — (possibly FAA registration/hex code)
  • Engine configuration data (CHT/EGT limits, aux channel names, etc.)

Plan.bak contains real waypoints with ICAO identifiers (KGYY, KVUJ, KIPT, 19A/KJCA, etc.) — confirms this is an active, configured aircraft.

6. Implications for Design

What's Confirmed

  • Demo files are the single source for both engine telemetry AND flight records
  • GPS data (lat/lon/alt/speed/track/date) is embedded in demo files
  • No separate logbook file exists on USB
  • Chart data structure matches Seattle Avionics installation instructions exactly
  • SQLite databases provide metadata for both currency checking and delta-copy logic
  • File naming convention is deterministic and parseable

What Needs Further Work

  1. DEMO binary format decoder — The record structure is identified but field mapping within engine data packets (type 0x02) needs reverse-engineering against known parameter values. Community tools on Vans Airforce and GRT Avionics forums should be sourced as references.
  2. E:ChartData handling — Safe to remove (reclaims ~8.4 GB). EFIS reads from root /ChartData/, not the E: prefixed path. Confirm deletion is non-destructive before automating.
  3. Logbook CSV import — Format is known and straightforward. Import is idempotent (full dump each time). Oil Added field provides sparse historical data to bootstrap oil consumption tracking.
  4. Continuation file assembly — Multiple +N files form one logical recording session. Parser must treat DEMO-{date}-{time}.LOG + all matching +N files as a single flight's data stream.
  5. Chart data staleness — ScannedCharts shows cycle 2411 (late 2024), but Plates shows 2606 (May 2026). Partial updates have occurred. Currency tracking needs to check each chart type independently.
  6. GRTCHARTS cleanup — Directory is a required flag; contents (E:GRTCHARTS) are disposable Windows artifacts.

Drive Identification for FR-1.2

The EFIS drive can be identified by the presence of:

  • Volume name: EFIS
  • AND/OR presence of GRTCHARTS/ directory at root
  • AND/OR presence of DEMO-*.LOG files at root
  • AND/OR presence of HHXRUp-proc.dat or NAV.DB at root

Any of these is sufficient; together they form a confident signature.

7. Logbook Data (Manually Saved CSV)

Key finding: The GRT HXr does NOT automatically write logbook data to USB. The pilot must manually trigger a save from the EFIS. When saved, it produces a CSV file.

Sample file: /Users/mwalker/Library/CloudStorage/Dropbox/Flying/Logbooks/Logbook 2025-01-15.csv

CSV Format

Date,Origin,Destination,Length,Length (hours),Fuel Used,Departure,Arrival,Hourmeter,Type,Passengers,Fuel Added,Oil Added
3/19/16,KLZU,KAND,0:29,0.4,0,15:13:14,15:43:10,49.6,VFR,,,
Column Type Notes
Date M/D/YY US short date format
Origin ICAO/FAA ID Airport identifier, sometimes blank (interrupted flights)
Destination ICAO/FAA ID Sometimes blank
Length H:MM Duration as hours:minutes
Length (hours) Decimal Same duration as decimal hours
Fuel Used Decimal Gallons consumed on that leg
Departure HH:MM:SS Time of departure (UTC based on GPS)
Arrival HH:MM:SS Time of arrival
Hourmeter Decimal Running hourmeter total (tach hours) — this is the cumulative value
Type String Always "VFR" in this dataset
Passengers Integer Sparse — only a few entries populated
Fuel Added Decimal Gallons added (very sparse)
Oil Added Decimal Quarts added (very sparse — values seen: 1, 6)

Key Observations

  • ~350 flight records covering Mar 2016 – Jan 2025 (356.5 tach hours total)
  • Home base: KLZU (Gwinnett County/Briscoe Field, GA)
  • Hourmeter provides continuous tach-hour reference for oil consumption tracking (FR-4.4)
  • Oil Added column exists but is extremely sparse — only a handful of entries have values. This confirms FR-4.2's manual-entry approach is correct; the logbook CSV alone is insufficient for oil trending.
  • Fuel Used is populated on most legs — useful for SFC trending (FR-5.4)
  • Some rows have blank Origin or Destination (GPS signal loss, aborted takeoffs, or multi-leg flights where the system lost track)
  • Last two rows are summary/blank (empty separator + total hours)
  • File is a snapshot of ALL history (not incremental) — each save overwrites/replaces the full logbook

Import Strategy

Since each logbook CSV is a complete dump (not incremental):

  1. Import should be idempotent — re-importing the same or newer CSV replaces old data
  2. Match on Date + Departure time as the unique key per flight record
  3. Oil Added entries from the CSV can seed historical oil data, but going forward, the menu-bar manual entry (FR-4.2) is the primary source
  4. The hourmeter value at each entry provides the tach-hours baseline for oil consumption rate calculation

8. Screenshots (SNAP####.PNG)

Pilot can manually save screenshots from the EFIS display. These appear as:

SNAP0001.PNG
SNAP0002.PNG
...
  • Numbered sequentially
  • Located at USB root
  • No processing required — archive as-is with date context
  • Should be moved off USB (cleaned) after archive, same as DEMO files
  • No screenshots currently on this drive (presumably cleared previously or not yet taken on this cycle)

9. Settings Files (Manual EFIS Settings Backup)

The EFIS allows manual backup of settings to USB. Files present:

  • Settings.bak — Full EFIS configuration (key=value, checksummed)
  • State.bak — Current EFIS state
  • WP.bak — User waypoints
  • Plan.bak — Flight plans

Archive strategy: These should be archived with a date stamp appended to the filename (e.g., Settings.bak → Settings-20260809.bak) since they're overwritten in-place on each save. History of settings changes has diagnostic value (e.g., if an EFIS setting change correlates with a performance anomaly).

Do not delete from USB — unlike DEMO and SNAP files, the EFIS may need these for restore.

10. GRTCHARTS Directory

Per pilot testing: the GRTCHARTS/ folder itself is required as a presence flag (the EFIS checks for it), but its contents are not needed. The E:GRTCHARTS subdirectory inside it is a Windows artifact and can be safely removed.

Automation rule: Preserve GRTCHARTS/ directory. Remove any contents within it (stale Windows artifacts). Never write chart data into this folder — charts go in /ChartData/.

11. Confirmed Aircraft Details

Item Value
Tail Number N488BF
Engine Lycoming IO-360 (4-cylinder, fuel-injected)
Cylinders 4 (CHT×4, EGT×4)
EFIS GRT Horizon HXr
Configuration Single EFIS, single aircraft
Home Base KLZU (Gwinnett County/Briscoe Field, GA)

12. Updated Capture Rules (FR-1.2 Refined)

On USB insertion, identify and handle these file types:

Pattern Type Action
DEMO-*.LOG Engine telemetry Move to archive (validate then delete from USB)
SNAP*.PNG Screenshots Move to archive (validate then delete from USB)
Logbook*.csv Logbook export Copy to archive (do NOT delete — pilot may re-export)
Settings.bak EFIS config Copy to archive with date stamp (do NOT delete)
State.bak EFIS state Copy to archive with date stamp (do NOT delete)
WP.bak Waypoints Copy to archive with date stamp (do NOT delete)
Plan.bak Flight plans Copy to archive with date stamp (do NOT delete)
HHXRUp-proc.dat EFIS firmware Leave untouched
NAV*.DB Nav database Leave untouched
ChartData/ Chart data Leave untouched (managed by currency subsystem)
GRTCHARTS/ Flag directory Leave untouched (clean internal contents only)

13. DEMO File Format Research (Community & Official Sources)

Key Discovery: Two Recording Mechanisms Available

The GRT HXr has two distinct data recording features (per GRT forum and documentation):

  1. DEMO Recording (currently in use) — Binary format, records full system state for replay on the EFIS itself. This is what produces the DEMO-*.LOG files on the drive. Contains settings, AHRS, GPS, EIS engine data, and display state. Undocumented binary format.

  2. USB Flight Data Logger (FDL) — Available on HXr/HX/SX/EX/Mini. Outputs CSV files directly (GRT FDL {number}.csv). Configurable recording interval (200ms–30000ms, default 1000ms). Includes AHRS and GPS data alongside engine parameters. Records automatically when: airspeed valid, ground speed >5 kts, RPM >0, or fuel flow >0. Not currently enabled on this aircraft (no FDL CSV files found on drive).

Recommendation: Enable the USB FDL feature on the EFIS (under SET MENU > General Setup > Demo Settings). Set recording interval to 1000ms (1 Hz, good balance of resolution vs. file size). This gives us structured CSV data without needing to reverse-engineer the binary DEMO format — dramatically simplifying Phase 2 engine data analysis. The DEMO recording can remain enabled as well for the full-fidelity replay capability, but the CSV FDL files become the primary data source for trending and analysis.

Configuration recommended:

  • USB Flight Data Logger: ON
  • USB FDL Record Interval: 1000 ms (1 second)
  • USB FDL Save Interval: 60 s (writes to USB every 60 seconds)

DEMO Binary Format (for archived files already on drive)

Based on hex analysis and community research:

Sources identified:

  • MATLAB GRTLogFileReader by Russell Carpenter — parses both EIS and AHRS data from GRT LOG files. Author obtained format documentation directly from GRT with permission. Available at git@gitlab.com:carpenaut1/GRTLogFileReader.git.
  • GRT EIS Log software — Official GRT Windows tool that decodes EIS engine data from DEMO files to spreadsheet/CSV format. Confirms that the EIS data subset is extractable.
  • Walter's Flight Data Recorder — Windows tool that decodes GRT EIS 2000/4000/6000 serial data in real-time. Documents the EIS serial protocol (header FE FF FE, 9600 baud, 8N1).
  • Vans Airforce forum thread on GRT EIS4000 serial data decoding — confirms the FE FF FE header for EIS data frames and that different firmware versions may use FE FE FE.

EIS Serial Data Protocol (relevant for record type 0x02 in DEMO files):

  • Header: 0xFE 0xFF 0xFE (or 0xFE 0xFE 0xFE for rare old firmware)
  • 9600 baud, 8N1 on serial; captured directly in DEMO binary as record type 0x02
  • Payload contains packed 16-bit values for: RPM, CHT×4/6/9, EGT×4/6/9, oil temp, oil pressure, fuel flow, fuel pressure, volts, amps, manifold pressure, tach hours, and aux channels
  • GRT's own EIS Log tool can decode this portion from DEMO files

AHRS Data (record type 0x01/0x13/0x14 in DEMO files):

  • Contains pitch, roll, yaw/heading, airspeed, altitude (pressure + density), vertical speed, angle of attack, G-force, OAT, wind, turn rate
  • The MATLAB GRTLogFileReader handles this, suggesting the format is documented (author received it from GRT upon request)

GPS Data (NMEA sentences embedded in records):

  • Standard NMEA-0183: $GPGGA, $GPRMC, $GPGSA, $GPGSV
  • Provides: lat, lon, GPS altitude, ground speed, ground track, satellite info, date/time
  • Already confirmed extractable from hex inspection

Strategy for Engine Data Analysis

Phase 2 approach (recommended):

  1. Going forward: Enable USB FDL → parse the CSV files directly (trivial)
  2. Historical data (existing DEMO files): Use GRT's official EIS Log tool (Windows, or via Wine/Crossover) to batch-decode the EIS portion to CSV, OR port the MATLAB GRTLogFileReader to Python for direct binary parsing of both EIS and AHRS data

Fallback/advanced: If full binary parsing is needed (for AHRS normalization per FR-3.7), contact GRT Avionics to request the serial interface documentation (they've provided it to others per the MATLAB author's note), then build a native Python parser.

EIS 4000 Parameters (4-cylinder IO-360)

Based on EIS 4000 documentation and Walter's Flight Data Recorder field list:

Parameter Resolution Notes
RPM 1 RPM Via tach pickup
CHT 1-4 1°F All 4 cylinders
EGT 1-4 1°F All 4 cylinders
Oil Temperature 1°F
Oil Pressure 0.1 PSI
Fuel Flow 0.1 GPH Via fuel flow transducer
Fuel Pressure 0.1 PSI
Bus Voltage 0.1 V
Bus Current (Amps) 0.1 A
Manifold Pressure 0.1 inHg Internal sensor on EIS 4000
Tach Time 0.1 hr Accumulated
Aux 1-6 Configurable User-defined (OAT, carb temp, etc.)
Fuel Quantity L/R Gallons If sensor installed

Plus AHRS/flight data (if available from EFIS records):

  • Pressure Altitude, Density Altitude
  • OAT (Outside Air Temperature)
  • Indicated Airspeed, True Airspeed
  • Vertical Speed
  • Pitch, Roll, Heading (magnetic)
  • G-force (vertical, lateral)