libdrone — Drone Maintenance and Operations Manual

About¶

Maintenance Planning Document (MPD), Aircraft Maintenance Manual (AMM), and Technical Log guidance for libdrone Pro. Covers pre-flight checks, scheduled maintenance intervals, crash inspection and repair procedures, GX12-7 connector maintenance, LiPo handling, and maintenance record-keeping.

About¶

This manual describes how to operate and maintain the libdrone Pro, the 6‑inch interceptor safely and reliably over its lifetime.

Document structure¶

It is divided into: 1. Maintenance Planning Document (MPD) — what to do and how often 2. Aircraft Maintenance Manual (AMM) — how to perform each task 3. Maintenance Logbook / Technical Log — how to record work and issues

Complementary documents¶

• reference/LD_-_Master_Specification_v246.md
• reference/LD_-_Hardware_v246.md
• reference/LD_-_Variables_v246.md
• operations/LD_-_DSRA_v246.md

Chapter 1 — Maintenance Planning Document (MPD)¶

1.1 Purpose¶

The MPD defines what maintenance tasks must be performed and how often for libdrone V2.4.6 to remain airworthy and within its design envelope.

1.2 Maintenance Task Table¶

1.3 Major Replacement Intervals (Guidelines)¶

These are engineering guidance values; real-world data should refine them.

• Motors: 150–250 flight hours or sooner if:
• Bearing noise increases
• Vibration signatures worsen in Blackbox
• ESC: 200–300 flight hours or after any severe electrical event
• Flight Controller: 300–500 hours or if repeated unexplained resets occur
• LiPo batteries: 150–200 cycles or if IR rises significantly or cells drift
• CF rods: inspect after each crash; replace if bent or scratched deeply

Chapter 2 — Aircraft Maintenance Manual (AMM)¶

2.1 General Data¶

• Frame: libdrone V2.4.6, 6‑inch True‑X
• Structure: X sandwich body (5-layer PCCF/tab/PCCF/tab/PCCF); PETG arm shafts + PETG tabs; ASA bumpers
• Spar: 4 × 2.0 mm OD CF rods, 258 mm length
• ESC: Pilotix 75A AM32 4‑in‑1 6S
• FC: Mateksys H7A3‑SLIM

Keep a printed exploded view or CAD screenshots in this section for fast reference when disassembling.

2.2 Propulsion System¶

2.2.1 Propeller Inspection & Replacement¶

Interval: quick check before every flight; detailed check every 10 flights.

Steps: 1. Remove battery and ensure drone is disarmed. 2. Inspect each prop: - Look for cracks, chips, stress whitening - Check X body T-slots and PCCF layers for cracks or deformation 3. Spin each motor/prop by hand: - Feel for resistance, rubbing, or notchy bearings 4. Balance check (every 10 flights): - Use a prop balancer; add small tape or lightly sand heavy blade 5. Replace any prop with visible damage, or if drone exhibits new vibrations in hover.

2.2.2 Motor Mount & Bearing Check¶

Interval: every 5 flights; after any crash.

Steps: 1. With battery removed, try to rock each motor gently: - There should be no lateral play at the mount 2. Check motor screws: - Confirm they are snug and nylon nuts are fully engaged in the passive cover pockets 3. Spin motor by hand and listen/feel: - A healthy motor is smooth and quiet - Gritty or notchy feel indicates bearing wear → schedule replacement

2.2.3 Floating Motor Mount — O‑ring & Sleeve Service¶

Inspection interval: every 10 flight hours. Replacement interval: every 20–30 flight hours.

Inspection steps: 1. Remove props and battery. 2. Loosen motor screws slightly and observe silicone sleeves and o‑rings: - Check for cracks, cuts, heavy compression set (flattened sections) 3. If any damage is found, schedule replacement for that motor.

Replacement steps: 1. Remove motor screws and passive cover carefully. 2. Remove old o‑rings and sleeves; clean any debris from bores. 3. Lightly lubricate new o‑rings with a small amount of silicone‑safe grease (if available). 4. Install new sleeves into bores and o‑rings into counterbores. 5. Reinstall passive cover and motor screws. 6. Tighten to 0.4–0.5 N·m — do not over‑tighten. 7. Verify: - No metal‑to‑arm contact - Motor can move microscopically under strong side load but is stable in normal use.

2.3 Electrical System¶

2.3.1 Battery Inspection¶

Interval: before every session; IR check every 10 flights.

Steps: 1. Visually inspect pack: - No swelling, punctures, or damaged shrink wrap 2. Check connectors: - XT60 housing intact; no exposed copper; solder joints solid 3. Measure cell voltages: - Healthy cells within ~0.02–0.03 V of each other at storage 4. Every 10 flights, measure IR (if charger supports it): - Track IR per cell over time - If IR rises sharply or one cell diverges, retire pack

2.3.2 ESC & Power Wiring¶

Interval: every 10 flights / after any crash.

Steps: 1. Visually inspect ESC: - No burnt components; conformal coating intact 2. Check capacitor leads: - No cracks at solder joints 3. Inspect XT60 and main leads: - No frayed insulation, no melted plastic 4. Verify MR30 connectors: - Housings not cracked; pins fully seated

2.3.3 Solder Joint Inspection Protocol¶

Interval: after every soldering session; before first power-on of any newly built or repaired assembly.

A cold or dry solder joint is the single most common cause of unexplained in-flight failures. Visual inspection under magnification catches most failures before they cost a flight.

Equipment: magnifying glass or loupe (×5–×10), good bench light, continuity tester.

Acceptance criteria — every joint must pass ALL of the following: * Shiny surface, not matte or granular (matte = cold joint, insufficient heat) * Concave fillet — solder wets up the wire and pad smoothly, no ball shape * No cracks at the junction between wire and solder * Wire fully tinned — no bare copper visible at joint base * No bridges between adjacent pads

Rejection criteria — replace immediately if ANY of the following: * Matte, dull, or crystalline surface * Visible crack or fracture line * Solder balled up rather than wetted to pad * Wire moves independently of solder blob when gently pushed * Any cold-looking connection on high-current joints (XT60, ESC power pads, motor pads)

High-current joints — additional check: After visual pass, use continuity tester across each joint. Then: connect battery via ShortSaver V2 and measure voltage drop across each MR30 connector at idle throttle. Any joint showing >50mV drop under minimal load is suspect — resolder.

Philosophy (Bardwell): If a joint looks wrong, it is wrong. Resolder it — solder is cheap, motors and ESCs are not.

2.3.4 Motor Direction Verification (Before First Props)¶

When: after any motor, ESC, or FC wiring change. Mandatory before maiden. Props must be REMOVED for this procedure.

Motor spin direction must match Betaflight motor layout. Incorrect direction on any motor causes immediate flip on takeoff.

Standard libdrone motor layout (props removed):

M1 (front-right): CCW
M2 (rear-right):  CW
M3 (rear-left):   CCW
M4 (front-left):  CW

Steps: 1. Remove all props. Verify visually — no props on any motor. 2. Connect battery. Connect FC to Betaflight Configurator via USB-C. 3. Navigate to: Motors tab. 4. Enable motor test slider (confirm props-off warning checkbox). 5. Raise M1 slider to ~10–15% throttle briefly. - Observe spin direction from above. - M1 (front-right) must spin CCW (counter-clockwise when viewed from above). 6. Return M1 to zero. Repeat for M2 (must be CW), M3 (CCW), M4 (CW). 7. If any motor spins wrong direction: - In ESC configurator (AM32): reverse motor direction for that motor. - Alternatively: swap any two of the three motor phase wires at the MR30 connector. 8. Repeat verification after any correction. 9. Only install props after all four motors confirmed correct.

Do not skip this step. A single reversed motor is not detectable by eye at rest.

2.3.5 Full Throttle Ground Test (Props Off)¶

When: before maiden flight; after any ESC or wiring replacement. Props must be REMOVED for this procedure.

Purpose: verify the electrical system sustains full load without voltage collapse, excessive heat, or component failure. Catches wiring faults, cold solder joints, and undersized connections before they cause a crash.

Equipment: battery (fully charged), Betaflight Configurator or OSD with current/voltage telemetry, ShortSaver V2 in circuit, timer.

Steps: 1. Remove all props. Confirm visually. 2. Connect fully charged 6S battery via ShortSaver V2. 3. Power on. Verify all systems nominal — no error beeps, GPS acquiring. 4. Connect to Betaflight Configurator OR confirm OSD voltage/current display active. 5. Note resting voltage (should be ~25.2V for full 6S). 6. Arm drone in a safe orientation (motors will spin — secure the drone physically or hold it firmly). 7. Gradually raise throttle to 50% for 5 seconds. Note: - Voltage sag: acceptable <1.0V drop under load - Current draw: typical ~20–30A at 50% throttle no-load (no props) - All four motors spinning, no unusual noise 8. Return to zero throttle. Wait 10 seconds. 9. Raise to 100% throttle for 3 seconds maximum. Note: - Voltage sag under full load - Any burning smell, unusual sound, or ESC heat - Current draw (typical ~40–60A no-load at full throttle) 10. Return to zero. Disarm immediately. 11. Disconnect battery. Check ESC temperature by touch — warm is acceptable, hot is not. 12. Check all solder joints and connectors visually — any discolouration indicates overload.

Pass criteria: * Voltage sag <1.5V at full throttle * No burning smell * ESC temperature: warm but holdable (< ~60°C) * All four motors spinning throughout * No ShortSaver V2 trip

Fail criteria — investigate before flight: * Any ShortSaver trip * Voltage sag >2V at full throttle * ESC too hot to touch after 3-second full throttle burst * Any motor stopping or stuttering * Burning smell from any component

2.4 Avionics¶

2.4.1 Firmware & Configuration Management¶

Interval: Quarterly or when new stable firmware is released.

Steps: 1. Backup Betaflight configuration (diff all / dump). 2. Backup ELRS model and RX config. 3. Backup HDZero profiles. 4. Perform firmware upgrades only when: - A stable version is available - You have time to test and re‑tune if needed 5. After any major firmware change: - Short hover test - Check Blackbox for abnormal vibrations or motor outputs.

2.4.2 GPS & Compass Calibration¶

Interval: Quarterly; after any significant crash or GPS mount change.

Steps: 1. Go to an open area away from metal structures. 2. Follow Betaflight compass calibration steps. 3. Confirm that home arrow and heading in OSD match actual orientation.

WIRE SEPARATION — COMPASS SENSITIVITY: The QMC5883L compass in M10Q measures Earth's magnetic field. Any current-carrying wire nearby creates a local magnetic field that corrupts heading data. During build and any rewiring: * Route all signal wires (GPS, UART, receiver) away from power wires * Power wires (battery leads, ESC phase wires) on opposite side of frame from signal wires wherever possible * Minimum 15mm separation between compass module and any high-current conductor * GPS bracket nose position already maximises distance from ESC and battery — do not route power wires forward along the body toward the bracket

2.5 Frame & Structure¶

2.5.1 Bolt Torque List¶

Use as guidance — exact torque depends on bolt class and material.

• M3 motor screws (into passive cover, nyloc nut):
• 0.4–0.5 N·m
• M3 sandwich bolts (through all 5 X body layers):
• 0.3 N·m — firm, do not crush PCCF
• M3 pinch slit bolts:
• Tighten gradually while checking rod play; do not over-clamp
• M2 shaft-to-tab screws (2× per tab, 16× per build):
• Finger tight + 1/4 turn
• M5 prop nuts:
• Snug plus small extra turn; avoid over-torqueing motor shafts

2.5.2 Arm Inspection & Replacement¶

Interval: every 5 flights; after any crash.

Inspection — shaft: 1. Look for cracks, whitening, or delamination in PETG shaft. 2. Check rod channel exits for chipping. 3. Ensure active and passive covers are fully seated. 4. Check tab junction face — no cracking at M2 screw holes.

Inspection — tabs: 1. Check T-lock engagement: grip tab and attempt lateral movement — zero play expected. 2. Inspect T-lock tip visible at inner edge of X body layer — no cracking. 3. Replace tab if T-lock shows any cracking or if lateral play is detectable.

Shaft replacement (crash — shaft broken, tabs intact): 1. Remove props and battery. 2. Disconnect MR30 motor connectors. 3. Remove 2× M2 screws per tab (4 screws total per arm). 4. Slide broken shaft off tabs — tabs remain in X body sandwich. 5. Slide new shaft onto tabs. Install 4× M2 screws. Finger tight + 1/4 turn. 6. Re-tension pinch bolt. Reconnect MR30. Acoustic ping check.

Full arm replacement (shaft + tabs, e.g. T-lock cracked): 1. Remove props and battery. 2. Disconnect MR30 motor connectors. 3. Remove M2 shaft-to-tab screws. Remove shaft. 4. Loosen sandwich M3 bolts (do not fully remove). 5. Slide tabs out of T-slots from outside edge. 6. Insert new tabs into T-slots — verify T-lock fully engaged, zero lateral play. 7. Re-torque sandwich M3 bolts to 0.3 N·m. 8. Install new shaft onto tabs. M2 screws. Pinch bolt. Reconnect MR30. 9. Acoustic ping check.

2.5.3 Rod Tension & Acoustic Ping Procedure¶

Goal: zero free play, acceptable resonance range.

Steps: 1. With drone unpowered, hold an arm near hub. 2. Gently tap rod with a non‑metallic tool. 3. Listen for clear “ping” in ~2.2–2.6 kHz band (or recorded via phone app). 4. If tone is dull or too low: - Increase pinch bolt tension gradually until play disappears 5. If tone goes very high before play is gone: - Risk of over‑stress; consider checking for misalignment or damage

Chapter 3 — Maintenance Logbook / Technical Log¶

3.1 Usage¶

Every significant maintenance event, anomaly, or configuration change must be recorded here. This enables:

• Trend detection (e.g. increasing vibration, shorter flight times)
• Root-cause analysis after incidents
• Documentation for warranty/insurance questions

3.2 Log Entry Template¶

Suggested log structure:

Maintain this log in either Markdown, spreadsheet, or paper form, but keep it close to the airframe.

Appendix A — Parts Reference (Summary)¶

For detailed specifications and weights, see reference/LD_-_Hardware_v246.md.

• Motors: 4 × 2507 1750 KV
• ESC: Pilotix 75A AM32 4‑in‑1 6S
• FC: Mateksys H7A3‑SLIM
• GPS: Matek M10Q‑5883
• Receiver: RadioMaster RP2 ELRS
• VTX: HDZero Freestyle V2 + camera
• Frame: PETG arms + PCCF plates + ASA bumpers
• Sensor Payload (optional): SEN66 + ESP32‑S3
• Video Payload (optional): Caddx Peanut 4K
• Payload Connector: GX12-7 male panel mount (×2, A+B), top-facing at X=±25mm, Y=−66mm

Appendix B — Operations Quick Reference¶

Before each flight: * Props & arms visually OK * Rods tight; no play by hand * Battery voltage OK; pack undamaged * GPS: ≥ 8 sats * RC & video links solid * Blackbox: logging enabled, storage >20% free (check via Betaflight OSD or Configurator) * GX12 cap: fitted and screwed tight if no payload; payload cable seated and locked if payload fitted * Payload (if fitted): physical master switch ON; OSD confirms payload active * Caddx Peanut (if fitted): internal battery charged; confirm charge alongside main LiPo before session

After each flight: * Motor temperature check — mandatory standing practice: Touch each motor bell within 60 seconds of landing. - Cool to warm (< ~45°C): nominal - Hot but holdable (~45–60°C): monitor trend over next flights; note in log - Too hot to hold (> ~60°C): ground drone, investigate before next flight Log motor temps after every session — trend detection catches bearing wear and winding issues before they cause in-flight failure. * Check for new vibrations or noises * Download Blackbox log — never overwrite without reviewing * Update logbook if any anomaly observed * Payload (if fitted): confirm WiFi sync complete before powering down ESP32 * Caddx Peanut (if fitted): flip AUX switch off before battery removal — allows clean file close

Appendix C — Field Procedures¶

C.1 Battery Swap Procedure (side-slide architecture, V2.4.6+)¶

The battery side-slides out of the RIGHT side of the drone. The payload mast does not need to be removed. The top layer stays sealed. Estimated time: <30 seconds.

1. Land and disarm.
2. Prop orientation — rotate each tri-blade prop by hand so one blade points straight UP. Two seconds per arm. This maximises lateral clearance for battery exit. No tools required.
3. Unclip battery strap buckle — buckle is on the RIGHT side, accessible without tools.
4. Slide battery RIGHT — battery exits the rail channel laterally. It clears the prop arc zone and arm root at this prop orientation.
5. Slide fresh battery in from RIGHT — push until it seats against the LEFT endstop wall.
6. Clip buckle closed.
7. Arm and fly.

Note: Payload mast remains untouched throughout. GX12 connector remains plugged throughout. The drone's platform surface is never disturbed by battery swaps.

C.2 Payload Connect / Disconnect Procedure¶

To fit a payload: 1. Confirm drone is disarmed and battery disconnected. 2. Align mast base over the 2× M3 boss pads (rear top surface, 20mm spacing). 3. Fasten 2× M3 × 8mm screws finger-tight, then ¼ turn with driver. 4. Remove GX12 dust cap from drone-side connector. Store cap in field bag. 5. Align payload cable GX12 female connector with drone-side male (align anti-rotation flats). 6. Screw lock ring until seated — finger tight is sufficient. 7. Flip physical master switch on mast to ON. 8. Connect drone battery — OSD should confirm payload active.

To remove a payload: 1. Disarm drone. Optionally disconnect battery. 2. Flip physical master switch on mast to OFF (or ensure radio AUX switch off). 3. Unscrew GX12 lock ring. Pull male connector clear. 4. Fit GX12 dust cap onto drone-side connector immediately. Screw tight. 5. Remove 2× M3 screws. Lift mast clear.

GX12 cap discipline: The dust cap must go back on the drone-side connector the moment a payload is removed. In the field this means the cap lives on the drone during flight — never loose in a bag where it can be lost. A spare cap lives in the field bag.

C.3 Payload Master Enable Logic¶

Each payload mast has two enable sources wired in OR logic:

Either source alone enables the payload. Both off = payload off, zero draw. Default state: both off. Payload is always off unless deliberately enabled.

Revision History¶

END — libdrone V2.4.6 Drone Maintenance & Operations Manual

Appendix D — Known Design and Operational Risks¶

Merged from operations/LD_-_DSRA_v246.md. Last reviewed March 2026. This appendix centralises all known design, manufacturing, assembly, and operational risks. Consult during CAD modelling, printing, assembly, tuning, and field operations.

This document centralises all known design, manufacturing, assembly, and operational risks for the libdrone V2.4.6 interceptor platform. It is intended to be consulted continuously during CAD modelling, 3D‑printing, assembly, tuning, and field operations.

Each risk includes: * ID — stable identifier for cross-referencing * Category — Design / Manufacturing / Assembly / Operational / Environmental * Description — Why this risk exists * Consequence — What happens if ignored * Mitigation — Exact steps to avoid or minimise the risk

CRITICAL DESIGN RISKS¶

R-DES-01 — Passive cover short‑circuiting floating motor mount¶

Category: Design / Assembly

Description: The passive arm cover must never touch the arm surface in the motor head zone. Only the o‑ring bosses may touch the o‑rings. Any additional contact defeats the floating isolation system.

Consequence: * Vibrations bypass isolation → severe gyro noise * Jello in footage * Reduced filter headroom * Potential for oscillations at high throttle

Mitigation: * Enforce FreeCAD section-view check on every revision * Confirm visible air‑gap in CAD * During printing/assembly, use feeler gauge or backlight test * If any contact occurs → reject part

R-DES-02 — Rod channel wall too thin (< 2.0 mm outer wall or < 1.5 mm to groove)¶

Category: Design / Structural

Description: The arm cross-section is highly optimised. PETG requires minimum wall thickness to avoid buckling, cracking, or deformation.

Consequence: * Arm twist under load * Rods punch through wall in crash * Loss of pre‑stress → frame resonance drops drastically

Mitigation: * Validate wall thickness via FreeCAD Section View > Measure * Respect variable constraints: - ≥ 2.0 mm rod channel → exterior - ≥ 1.5 mm groove bottom → rod channel * Reject prints that show under-extrusion in rod channel region

R-DES-03 — Incorrect rod channel diameter¶

Category: Design

Description: Using rod channel = 2.0 mm (same as rod OD) removes all clearance. libdrone requires: * #RodDia = 2.0 mm * #RodDiaChannel = 2.2 mm

Consequence: * Assembly impossible or damages rods * Excessive friction prevents proper pre‑tension * Rods may buckle on insertion

Mitigation: * Always use variable-based modelling * Never override #RodDiaChannel * Validate with printed coupons

R-DES-04 — Improper rod offset ordering (orientation error)¶

Category: Design / Assembly

Description: The 4‑rod box-girder depends on offsets: +5, +2, −2, −5 mm. Installing arms in the wrong orientation breaks the structural logic.

Consequence: * Rod collision at hub * Inability to pass rods through frame * Frame loses torsional rigidity

Mitigation: * Arm labels in CAD must indicate "This side UP" for FL/RL * Provide assembly diagram in DMOM * Verify rod plane order in CAD assembly BEFORE printing

[1] MANUFACTURING RISKS (3D PRINTING)¶

R-MFG-01 — Poor interlayer adhesion (PETG arms)¶

Category: Manufacturing / PETG behaviour

Description: Vertical-force and torsion loads rely heavily on layer adhesion. PETG is sensitive to cooling and draft airflow.

Consequence: * Arm splitting along layer lines * Motor mount deformation * Rod channel integrity compromised

Mitigation: * Enclosure closed during print * Use recommended PETG temperatures * Perform coupon break tests on every parameter change

R-MFG-02 — PCCF top plate warping¶

Category: Manufacturing / PCCF

Description: PCCF has high contraction and must be printed with heat‑soak stability.

Consequence: * Stack no longer sits flat * Mast inserts misaligned * Rod holes accumulate positional error

Mitigation: * Use glue stick on textured plate * Allow slow cooling on bed to ~60°C * Reject plates with >0.6 mm warp

R-MFG-03 — Over‑extrusion causing channel constriction¶

Category: Manufacturing / Calibration

Description: Over‑extrusion reduces functional clearances (rod channels, groove walls).

Consequence: * Rod insertion problems * Passive cover interference * Cable groove becoming too tight

Mitigation: * Calibrate e‑steps and flow rate * Print rod channel coupons first * Verify channel with drill-bit gauge (2.2 mm target)

[2] ASSEMBLY RISKS¶

R-ASM-01 — Insufficient rod pre‑tension¶

Category: Assembly

Description: Rod tension must eliminate all play at joints.

Consequence: * Low‑frequency rattling under throttle * Resonance drop → jello * Higher crash damage due to rod slap

Mitigation: * Use pinch slit screw to tension until zero play by hand * Verify acoustic ping ~2.2–2.6 kHz

## R-ASM-02 — Over‑tightening motor mount screws¶

Category: Assembly

Description: Motor screws clamp nylon-insert nuts inside passive cover pockets. Too much torque compresses silicone sleeves.

Consequence: * Loss of motor isolation * Sleeve tearing * Motor misalignment

Mitigation: * Torque to 0.4–0.5 N·m only * Replace sleeves every 20–30 flight hours

R-ASM-03 — Misaligned MR30 connections¶

Category: Assembly / Electrical

Description: MR30 connectors must match labelled motor numbers.

Consequence: * Incorrect motor order → instant tip‑over * Dangerous behaviour on arming

Mitigation: * Label M1–M4 clearly on heatshrink * Verify continuity with multimeter

[3] OPERATIONAL RISKS¶

R-OPS-01 — Flying with damaged o‑rings or sleeves¶

Category: Operational

Description: Silicone parts degrade under vibration and must be replaced.

Consequence: * Sudden isolation failure → severe vibration * Unstable flight * Motor screw loosening

Mitigation: * Inspect o‑rings/sleeves every 10 hours * Replace every 20–30 hours

## R-OPS-02 — PETG arm brittleness in cold weather¶

Category: Operational / Environmental

Description: PETG loses toughness near or below 0°C.

Consequence: * Arm cracking on minor impact * Reduced crash tolerance

Mitigation: * Avoid operation < 0°C with PETG arms * Use spare arms printed in identical PETG

R-OPS-03 — Low satellite count before arming¶

Category: Operational / Safety

Description: GPS must lock ≥ 8 satellites for reliable Rescue.

Consequence: * GPS Rescue may drift or fail * Risk of flyaway

Mitigation: * Wait for ≥ 8 satellites * Verify stable HDOP in Betaflight

[4] ENVIRONMENTAL & ELECTRICAL RISKS¶

R-ENV-01 — Moisture ingress into electronics¶

Category: Environmental

Description: Flight in fog, rain, or crash into wet grass introduces moisture.

Consequence: * Short circuits * VTX/ESC/FC damage

Mitigation: * Conformal coat FC/ESC/VTX/RX before maiden * Open frame after wet crash and allow full drying

R-ENV-02 — VBAT spikes damaging electronics¶

Category: Electrical

Description: High-throttle transitions can produce voltage spikes.

Consequence: * FC or VTX brownout or permanent damage

Mitigation: * Use Pilotix 75A AM32 with integrated TVS * Retain 1000µF low‑ESR capacitor END — libdrone V2.4.6 Risk Register

V2.4.6 Architecture Risks¶

R-STR-04: T-lock tab pull-out failure¶

Risk: Tab T-profile fails to engage properly in PCCF T-slot. Tab pulls out under crash load. Probability: Low if Coupon 8 passes before production. Impact: High — arm detaches from body. Mitigation: Coupon 8 mandatory before X body production. Inspect T-lock seating before every flight. Trigger: Any crash → inspect T-lock before next flight.

R-STR-05: PCCF T-slot fracture under bending load¶

Risk: T-slot pocket weakens PCCF layer excessively. Layer fractures at T-slot under crash load. Probability: Low — T-slot positioned in X extension zone, not core. Impact: High — structural failure of X body. Mitigation: Coupon testing of T-slot geometry. Minimum 3 mm wall around all T-slot features. Wall check in CAD cross-section view before printing.

R-STR-06: Rod channel misalignment across sandwich layers¶

Risk: Rod channels in 5 sandwich layers do not align — rod cannot thread through or binds. Probability: Low if rod threading used as alignment step. Impact: Medium — assembly blocked; layers must be re-drilled or reprinted. Mitigation: Thread rods as part of sandwich assembly — rods self-align layers. Verify channel alignment in FreeCAD Assembly cross-section view before printing.

R-ELE-03: Electronics flat layout interference¶

Risk: Components placed flat on X body interfere with each other (RF, thermal, physical). Impact: Medium — noise on GPS, FC, or VTX. Mitigation: GPS on front bracket, away from ESC. Conformal coating on all PCBs. Minimum 5 mm separation between GPS bracket and ESC in layout. Verify in CAD.

R-MFG-03: Arm shaft vertical print failure¶

Risk: Tall vertical PETG print fails mid-print or delaminates at brim. Probability: Medium — vertical prints are less stable than flat. Impact: Low — single shaft waste; reprint. Mitigation: 5 mm brim mandatory. Enclosure door closed. PID temperature tuning. Print one shaft first; verify before batch.

END OF FILE

Revision History¶