C31 Maintenance Repair Manual V1.0

C31 Maintenance Repair Manual V1.0

C31 Maintenance Repair Manual V1.0

Maintenance & Repair Manual (V1.0)
Ceres Air LLC
January 2026
Revision History
Title
Title
Title
Version
Revision Date
Description
V1.0
12/30/25
Testing Services Department-First Release

1. Disassembly and Assembly Overview

This section covers the disassembly and assembly of key components of the 2025 C31 Transport Unmanned Aircraft and its associated mission systems.
In most cases, the assembly process is the reverse of the disassembly process. However, for certain structures, the installation sequence differs from the assembly process. Please read the instructions carefully.
Before disassembling any structural components or electronic parts, ensure that all power cables, communication cables and hoses have been disconnected, verify that the battery is powered off. Hot-plug maintenance of the aircraft is strictly prohibited.

2. Disassembly and Assembly Requirements

Before disassembling, verify the extent of equipment damage and complete a repair or maintenance plan based on a thorough review of all applicable manuals. Components shall only be replaced after confirming that they meet replacement criteria or that actual damage may pose a safety risk to the equipment.

3. Disassembly & Assembly Environment

Disassembly and assembly operations must be performed indoors with adequate lighting. During maintenance, the aircraft shall be placed in a designated maintenance area and on an approved workbench.
Small removed parts shall be stored in organizers or suitable containers. Electrical components shall be kept away from water sources and must not be placed arbitrarily. Sharp or fragile components shall be wrapped or protected with foam or other protective materials before storage to prevent damage.

4. Pre-Disassembly Preparations

After verification of the aircraft or mission system condition and completion of the repair plan, the aircraft or the relevant mission system to be disassembled shall be surface-cleaned prior to disassembly. Disassembly work may only begin after basic cleaning has been completed and the equipment has fully air-dried.

5. Disassembly and Assembly Tool List

Disassembly and assembly tools are essential for UAV maintenance operations and include hand tools, power tools, calibration tools, auxiliary tools and consumables. These tools may present certain hazards during use. Therefore, all tools shall be operated strictly in accordance with the Tool Usage Guidelines to prevent improper operation that could result in personal injury or property damage.
Title
Title
Title
Title
Tool Category
Tool Name
Specifications:
Application
Hand tools
Hex Key Set
N/A
Drone disassembly and assembly
Ratchet Wrench
N/A
Drone disassembly and assembly
Power tools
Electric screwdriver
12-14V interchangeable bits
Drone disassembly and assembly
calibration tools
Torque wrench
Electronic torque wrench
After installation, torque verification at specified measurement points
Auxiliary tools
Right-Angle Adapter
N/A
Used with electric screwdriver for fastener removal/installation in confined spaces
Cable Threader
N/A
Cable routing guidance in arms and confined areas
Consumables
Marker Pen
N/A
After the screws are tightened, make anti-loosening marks
Threadlocker
IOCTITE 277
Apply before installing screws to prevent anti-loosening
Penetrating Oil
WD-40
Loosen the rust screws before disassembly
Electrical tape
Minor cable insulation repair (non-power cables only)
Acetate tape
Abrasion protection for cables and hoses

5.1. C31 Airframe Disassembly & Assembly Guide

Screw specifications and installation requirements
Title
Title
Title
Title
Serial number
Screw specifications
Screw material number
Torque requirements
1
M5*12
126-000987
2.5+0.25NM
2
M4*12
126-000288
2.0+0.2NM
3
M4*10
126-000955
2.0+0.2NM
4
M5*10
126-001001
2.5+0.25NM
5
M4*22
126-001092
2.0+0.2NM
6
M5 circlip
126-000985
7
Landing gear buckle shaft
126-002447
Installation Procedure
    Insert the left liner plate and right liner plate into the corresponding latch positions on the left and right beams. Secure each liner plate using two (2) M4 × 10 stainless steel flanged hex socket machine screws.
    Match the identification numbers of the left and right beams with the corresponding numbers on the inner joints, then insert them accordingly. As shown in the illustration, secure the front side of the left and right beams to the inner joints using a total of twelve (12) M4 × 10 stainless steel flanged hex socket machine screws (apply threadlocker as a priority).
    Install the four (4) battery tray assemblies onto the locating pins of the left and right beams. Secure them using a total of eight (8) M4 × 12 stainless steel hex socket machine screws (apply V-68 threadlocker as a priority) and eight (8) M4 × 22 stainless steel hex socket machine screws.
    Install the four (4) landing gear latch bases onto the left and right cross beams according to the anti-misinstallation (keyed) orientation. Secure each base using four (4) M5 × 12 stainless steel hex socket machine screws. Pay close attention to the installation direction of each base and confirm orientation based on the battery tray assemblies.
    Insert the front and rear beams into the inner joints according to the corresponding identification numbers. Secure the front side of the airframe using a total of sixteen (16) M4 × 10 stainless steel flanged hex socket machine screws (apply threadlocker as a priority).
    Flip the airframe over and secure it using a total of thirty-two (32) M4 × 10 stainless steel flanged hex socket machine screws in the red-marked areas, along with twelve (12) M5 × 10 stainless steel flanged hex socket machine screws in the yellow-marked areas (apply threadlocker as a priority).
    Secure both the inner and outer sides of the front and rear beams using a total of sixteen (16) M4 × 10 stainless steel flanged hex socket machine screws (apply threadlocker as a priority).
    Install the four (4) landing gear latch assemblies by inserting one (1) landing gear latch shaft through each latch base. Ensure the wrench orientation faces the front of the airframe, then secure each shaft with one (1) M5 retaining ring (circlip)
Disassembly Procedure
    Remove the M5 retaining ring (circlip) from each landing gear latch shaft. Pull the latch shafts out of the latch bases, then remove the four (4) landing gear latch assemblies.
    Remove the sixteen (16) M5 × 12 stainless steel hex socket machine screws securing the landing gear latch bases, then remove the latch bases.
    Remove the eight (8) M4 × 22 stainless steel hex socket machine screws on the upper side of the battery tray assemblies and the eight (8) M4 × 12 stainless steel hex socket machine screws on the inner side of the battery tray assemblies, then remove the battery tray assemblies.
    Remove the ninety-two (92) M4 × 10 stainless steel flanged hex socket machine screws and the twelve (12) M5 × 10 stainless steel flanged hex socket machine screws from the airframe assembly.
    Pull the front and rear beams outward along with the left and right beams to separate them from the inner joints and main beams, then remove the left and right liner plates.

5.2. C31 Frame Module Disassembly & Assembly Guide

Screw specifications and installation requirements
Title
Title
Title
Title
Serial number
Screw specifications
Screw material number
Torque requirements
1
M3*8
126-000282
1.0±0.1NM
2
Φ5*12+M4*8
126-000296
1.5±0.15NM
3
M4*12
126-000922
1.5±0.15NM
4
φ5*5+M4*8
126-000754
1.5±0.15NM
5
M4*10
126-000955
1.5±0.15NM
6
Φ4*3+M3*6
126-000789
0.8±0.08NM
7
M4*18
126-000877
1.5±0.15NM

Installation Procedure
    Using appropriate tools, install the rotating radar adapter carbon plate onto the optional radar according to the contoured mounting position and secure it with four (4) M4 × 10 Stainless Steel Socket Flange Machine Screws.
    Using appropriate tools, secure the monocular module to the monocular bracket in the keyed (anti-misinstallation) orientation using four (4) M4 × 10 Stainless Steel Socket Flange Machine Screws.
    Place the airframe upside down on the support plate. Apply threadlocker and secure the monocular bracket assembly from the top and front sides using a total of eight (8) M4 × 18 Stainless Steel Socket Flange Machine Screws.
    Secure the left and right nose cable clips to the airframe from the top and front sides using a total of five (5) M4 × 10 Stainless Steel Socket Flange Machine Screws.
    Secure the nose silicone cable clips to the airframe in the orientation shown using eight (8) Φ4 × 3 + M3 × 6 Stainless Steel Shoulder Screws.
    Secure the single radar module to the monocular bracket in the keyed (anti-misinstallation) orientation using four (4) M3 × 8 Stainless Steel Knurled Head Socket Cap Screws.
    Secure the two (2) avionics adapter brackets to the airframe from the front and inner sides using six (6) M4 × 10 Stainless Steel Socket Flange Machine Screws. Pay close attention to the installation orientation of the adapter brackets.
    Apply threadlocker to four (4) M4 × 10 Stainless Steel Socket Flange Machine Screws, then secure the avionics module to the inner side of the front beam. Route the antennas outward on both sides and pass the three-in-one wiring harness through the center hole of the monocular bracket.
    Secure the two (2) RTK antenna brackets in the keyed positions using a total of six (6) M4 × 10 Stainless Steel Socket Flange Machine Screws. Install the RTK rubber grommets and antennas, ensuring the flat side of each grommet faces downward. Secure the two RTK silicone cable clips to the designated positions on the frame using one (1) Φ5 × 5 + M4 × 8 Stainless Steel Shoulder Screw each, then clip the left and right RTK antennas into the cable clip slots.
    Secure the rotating radar bracket to the airframe from the front and forward sides using a total of eight (8) M4 × 12 Stainless Steel Socket Flange Machine Screws.
    Secure the interface board module to the rotating radar bracket using five (5) M6 × 12 × 1 Stainless Steel Flat Washers and five (5) Φ5 × 12 + M4 × 8 Stainless Steel Shoulder Screws.
    Secure the rotating radar pre-assembled unit to the rotating radar bracket in the keyed orientation using four (4) M3 × 8 Stainless Steel Knurled Head Socket Cap Screws (apply threadlocker as a priority).
Disassembly Procedure
    Using appropriate tools, remove four (4) M3 × 8 Stainless Steel Knurled Head Socket Cap Screws and remove the rotating radar assembly.
    Remove four (4) M3 × 8 Stainless Steel Knurled Head Socket Cap Screws and remove the rotating radar.
    Remove five (5) M6 × 12 × 1 Stainless Steel Flat Washers and five (5) Φ5 × 12 + M4 × 8 Stainless Steel Shoulder Screws, then remove the interface board plate.
    Remove eight (8) M4 × 12 Stainless Steel Socket Flange Machine Screws and remove the rotating radar bracket.
    First remove two (2) Φ5 × 5 + M4 × 8 Stainless Steel Shoulder Screws, then remove the RTK silicone cable clips.
    Remove the left and right RTK antennas and the RTK rubber grommets.
    Remove six (6) M4 × 10 Stainless Steel Socket Flange Machine Screws, then remove the two (2) RTK antenna brackets.
    Remove four (4) M4 × 10 Stainless Steel Socket Flange Machine Screws and remove the avionics module from the inner side of the front beam.
    Remove six (6) M4 × 10 Stainless Steel Socket Flange Machine Screws and remove the avionics adapter brackets.
    Remove four (4) M3 × 8 Stainless Steel Knurled Head Socket Cap Screws and remove the single radar module.
    Remove eight (8) Φ4 × 3 + M3 × 6 Stainless Steel Shoulder Screws and remove the nose silicone cable clips.
    Remove five (5) M4 × 10 Stainless Steel Socket Flange Machine Screws and remove the left and right nose cable clips.
    Remove eight (8) M4 × 18 Stainless Steel Socket Flange Machine Screws and remove the monocular bracket assembly.
    Remove four (4) M4 × 10 Stainless Steel Socket Flange Machine Screws and remove the monocular module

5.3. C31 Propulsion Assembly Disassembly & Assembly Guide


Screw specifications and installation requirements
Title
Title
Title
Title
Serial number
Screw specifications
Screw material number
Torque requirements
1
M3*6
126-000975
0.8±0.08NM
2
M6*25
126-000759
7.0±0.7NM
3
M6 elastic pad
126-000251
4
M4*8
126-000962
1.0±0.1NM
5
M3*10
126-000953
0.8±0.08NM
6
M3*8
126-000282
0.8±0.08NM
7
Motor adapter plate locking bolts
201-002815
20±2NM
8
M4*10
126-000287
1.5±0.15NM
9
5*4+M4*8
126-000639
1.5±0.15NM
Installation procedure
    Align the locating pins on the bottom of the two motor lower covers with Adapter Plate B1/3 and Adapter Plate B5/7, respectively. Secure each using four (4) M3 × 6 Stainless Steel Socket Flange Machine Screws.
    Apply one drop of threadlocker to each of the opposing threaded inserts on the four threaded holes at the bottom of the motor. Secure the two adapter components to the bottom of the CCW motor using four (4) M6 × 25 carbon steel hex socket screws with M6 spring washers, with threadlocker applied. Pay attention to the installation orientation of the motor lower cover.
    Apply grease evenly around the circumference of the two grommets on the front side of the power wiring harness. Secure the ESC assembly corresponding to Adapter Plate B1/3 to the power harness: first install the positive and negative waterproof compression seals onto the specified positions of the harness connectors, insert the connectors according to the orientation where the copper lugs contact the ESC main board terminals and secure using two (2) M4 × 8 Stainless Steel Socket Flange Machine Screws.Secure the ESC assembly corresponding to Adapter Plate B5/7 to the power harness using two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws for the upper power harness and two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws for the lower power harness.
    Apply grease to all grommets on the signal cables. Secure the upper and lower power harnesses using two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws, then secure the front arm ESC signal harness to the designated position on the ESC lower housing using two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws.
    Attach the positive and negative terminal cover gaskets to the specified positions on the inner side of the terminal covers and press firmly into place. Install the two waterproof cover sealing rings into the two grooves of each terminal waterproof cover and apply white grease evenly around the circumference. Secure the waterproof covers to the designated positions using four (4) M3 × 6 Stainless Steel Socket Flange Machine Screws.
    Apply grease to all grommets on the signal cables, then secure the front arm ESC signal harness to the designated position on the ESC lower housing using two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws. Perform an airtightness test in accordance with the parameters specified in the airtightness guideline.
    Organize the signal cables and power harnesses using two ESC lower-housing cable clamps (one upper and one lower). Secure them to the designated positions on the ESC lower housing using two (2) M3 × 8 Stainless Steel Knurled Head Socket Cap Screws.
    Apply grease evenly around the circumference of the two front grommets on the motor three-phase cables. Insert the three-phase cables into the front-side connectors of the ESC according to the contoured alignment. Secure each copper lug of the three-phase cables to the ESC main board terminals using one (1) M4 × 8 Stainless Steel Socket Flange Machine Screw per phase.
    Attach the three-phase terminal cover gasket to the specified position on the inner side of the cover and press firmly into place. Install the two waterproof sealing rings into the two grooves of the waterproof cover and apply white grease evenly around the circumference. Secure the ESC three-phase waterproof cover to the designated position on the ESC assembly using four (4) M3 × 6 Stainless Steel Socket Flange Machine Screws.
    Secure the motor three-phase cable connectors to the ESC housing using four (4) M3 × 10 Stainless Steel Socket Flange Machine Screws.
    According to the orientation of the end joint, install the two motor assemblies into the outer arm assembly at the upper 1/3 position and lower 5/7 position, respectively. Secure them from the front and rear sides using a total of eight (8) motor adapter plate locking bolts (apply threadlocker as a priority). Insert the carbon tube protective sleeve into the front side of the arm, with the notch facing upward.
    Secure the two ESCs to the designated brackets on the outer arm assembly using eight (8) M4 × 10 Stainless Steel Knurled Head Socket Cap Screws.
    Route the power harness and signal harness through the front through-holes of the arm and out of the arm. Secure the two three-phase cable fixing bases to clamp the ESC cables on both sides using three (3) M3 × 10 Stainless Steel Socket Flange Machine Screws per base. Secure the two three-phase cable pressure plates over the three-phase cables using two (2) Stainless Steel Shoulder Screws per plate, fastening them to the fixing bases.
    Secure the hose clamps in the orientation shown using six (6) Φ5 × 4 + M4 × 8 Stainless Steel Shoulder Screws, ensuring the arrow points toward Adapter Plate B1/3 on the upper side. Apply the No. 1 identification label to the arm
Disassembly Process
    Remove six (6) Φ5 × 4 + M4 × 8 Stainless Steel Shoulder Screws and remove the hose clamps.Note: Maintain component integrity during removal.
    Remove the shoulder screws from the two three-phase cable pressure plates, then remove the pressure plates. Next, remove two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws from each three-phase cable fixing base, remove the fixing bases and pull the power harness and signal harness out through the front through-holes of the arm. Organize the harnesses.
    Remove eight (8) M4 × 10 Stainless Steel Knurled Head Socket Cap Screws and remove the two (2) ESCs from the designated brackets on the outer arm assembly.
    Remove four (4) M3 × 10 Stainless Steel Socket Flange Machine Screws and four (4) M3 × 6 Stainless Steel Socket Flange Machine Screws from the ESC. Using appropriate tools, remove the three-phase terminal cover gasket.
    Remove three (3) M4 × 8 Stainless Steel Socket Flange Machine Screws from the copper lugs of the three-phase cables and remove the motor three-phase cables (repeat for the opposite side).
    Remove the motor adapter plate locking bolts (eight (8) total). After removal, clean any residual threadlocker. Remove the two motor assemblies from the outer arm assembly and remove the arm carbon tube protective sleeves (store properly after removal).
    Remove two (2) M3 × 8 Stainless Steel Knurled Head Socket Cap Screws from the ESC lower-housing cable clamps, release the fixation of the signal cables and power harnesses and organize the harnesses.
    Remove two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws, detach the front arm ESC signal harness from the designated position on the ESC lower housing and clean any grease residue from the grommets on the signal cables.
    Remove four (4) M3 × 6 Stainless Steel Socket Flange Machine Screws from the positive and negative terminal waterproof covers, remove the covers and clean off the white grease around the circumference.
    Remove two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws and two (2) M4 × 8 Stainless Steel Socket Flange Machine Screws from the ESC. Disconnect the harness connectors and clean grease residue from the grommets on the harnesses.
    Remove four (4) M6 × 25 carbon steel hex socket screws with M6 spring washers securing the two adapter components to the bottom of the CCW motor. Clean any residual threadlocker from the threaded inserts on the four threaded holes at the bottom of the motor.
    Remove the M3 × 6 Stainless Steel Socket Flange Machine Screws (four per side) connecting the motor lower covers to Adapter Plate B1/3 and Adapter Plate B5/7. Separate the motor lower covers from the two adapter plates.Caution: Control torque during removal to prevent thread stripping.
    Classify and store all removed components by type. Clean threadlocker and grease residue from component surfaces. Inspect component integrity (e.g., screws, spring washers, sealing rings, gaskets and other wear items) and apply identification labels to facilitate subsequent reassembl

Note: The installation and disassembly procedures for Arms No. 2, No. 3 and No. 4 are the same as those for Arm No. 1 and are therefore not repeated here. When performing installation or disassembly on Arms No. 2, No. 3 and No. 4, ensure that the motor rotation direction corresponds correctly to the adapter component numbering.

5.4. C31 Flight Platform Disassembly & Assembly Guide



Screw specifications and installation requirements
Title
Title
Title
Title
Serial number
Screw specifications
Screw material number
Torque requirements
1
M6*8
126-000954
3.0±0.3NM
2
M4*14
126-000749
1.5±0.15NM
3
M3*20
126-000751
0.8±0.08NM
4
M4*12
126-000288
1.5±0.15NM
5
M8*25
126-000957
17.0±0.5NM
6
M6*12
126-001090
8.0±0.8NM
7
M4*12
126-000922
1.5±0.15NM
8
M8*20
126-000748
15.0±0.5NM
9
M4*10
126-000955
1.5±0.15NM
10
M3*15
126-000744
0.8±0.08NM
Installation procedure
    Apply threadlocker to the four threaded holes on the mounting surface of the LiDAR. Secure the LiDAR adapter carbon plate in the orientation shown using four (4) M6 × 8 Stainless Steel Low-Profile Socket Head Machine Screws.
    Connect the LiDAR wiring harness to the LiDAR.
    Secure the four joint locking assemblies to the designated positions on the four inner arm assemblies using two (2) M4 × 14 Stainless Steel Socket Flange Machine Screws per assembly, fastening from the inner side toward the outer side.
    Insert the two video transmission antennas into the through-holes at the bottom of Inner Arm No. 3 and Inner Arm No. 4, respectively and route the antennas out through the rear exit holes.
    Secure the video transmission antenna clamps to Inner Arm No. 3 and Inner Arm No. 4 using two (2) M3 × 20 Stainless Steel Socket Flange Machine Screws per clamp, with all screws installed from right to left.
    Secure the power distribution board (PDB) cable compartment to the left and right beams at the locating pin positions using a total of eight (8) M4 × 12 Stainless Steel Socket Head Machine Screws, fastening from the front and side.
    Insert the four pre-assembled inner arm assemblies into the frame inner joints according to their respective numbering and the limiting slots. First route the two video transmission antennas through the frame pass-through holes and out toward the nose side. Then secure each inner arm assembly using four (4) M8 × 25 Stainless Steel Socket Head Machine Screws (apply threadlocker beforehand).
    Secure the inner joints to the frame using a total of sixteen (16) M6 × 12 Stainless Steel Socket Head Machine Screws (upper and lower positions; apply threadlocker beforehand).
    Remove the four joint shafts from the four outer propulsion assemblies. Insert the four outer arm propulsion assemblies into the corresponding four inner arm assemblies and route the harnesses through. Reinsert the joint shafts and secure each using one (1) M8 × 20 Stainless Steel Socket Flange Machine Screw, fastening uniformly from top to bottom.
    Secure the pre-assembled LiDAR module to the designated upper position on the monocular bracket using four (4) M4 × 10 Stainless Steel Socket Flange Machine Screws.
    Route the four power harnesses from the arms through the frame and out via the center pass-through hole. Route two ESC signal harnesses (1-to-2) and two video transmission antennas out through the front side of the frame. Insert the battery communication & power supply harness into the designated keyed connector on the interface board, then route it together with the PDB load power adapter harnesses through the front sides and out via the center pass-through hole.
    Insert the eight power leads into the corresponding eight keyed connectors on the PDB assembly, matching colors (white to white, black to black) and engage the eight connector safety latches. Insert the battery communication & power harness and the load power adapter harnesses into their respective keyed connectors at the designated locations.
    After placing all harnesses neatly into the cable compartment, secure the PDB assembly to the compartment using ten (10) M4 × 12 Stainless Steel Socket Flange Machine Screws, then insert the four screw plugs.
    Insert the load control adapter cable and the rear radar adapter cable in their keyed orientations. Then route the load power adapter harness coming from the PDB together and clip them sequentially into the right-side nose cable clips. Secure the right nose cable clip pressure plate using two (2) M4 × 10 Stainless Steel Socket Flange Machine Screws.
    Route the rotating radar harness from the top according to the diagram and insert it into the connector. Ensure that the antennas on both sides are routed inside the ESC harnesses.For configurations without LiDAR, insert the 2+10-pin connector dummy plug into the LiDAR port on the interface board; no fastening screws are required.
    Insert the connectors for avionics, ESC signal lines, radar and front camera into the designated keyed ports on the interface board. Secure using a total of thirty (30) M3 × 15 Stainless Steel Socket Flange Machine Screws. Arrange the ESC signal harnesses, communication harnesses and load power harnesses into the cable clips on both sides according to diameter, position and natural routing.
    Connect the RTK antennas and video transmission antennas. Apply yellow adhesive at the video transmission antenna connection points. Place the connectors at the designated positions in the center of the bottom cable clip, then clip the antennas into place.
    On the tail side, secure the two tail joint cable covers to the designated positions using two (2) M4 × 10 Stainless Steel Socket Flange Machine Screws per cover
Disassembly procedure
    Remove the M4 × 10 Stainless Steel Socket Flange Machine Screws from the two tail joint cable covers and remove the tail joint cable covers.
    Disconnect the RTK antennas and video transmission antennas. Remove the yellow adhesive from the video transmission antenna connection points, take the antennas out of the bottom cable clips and disconnect the connectors.
    Remove thirty (30) M3 × 15 Stainless Steel Socket Flange Machine Screws, then disconnect the harness connectors for avionics, ESC signal lines, radar and front camera (disconnect in the reverse direction of the keyed interfaces on the interface board). Release the cable clips on both sides and remove the ESC signal harnesses, communication harnesses and load power harnesses.
    For configurations without LiDAR, remove the 2+10-pin dummy plug from the LiDAR port on the interface board.For configurations with rotating radar, disconnect the connector and organize the rotating radar harness.
    Remove two (2) M4 × 10 Stainless Steel Socket Flange Machine Screws from the right pressure plate of the right-side nose cable clip, remove the pressure plate and take out the load control adapter cable, rear radar adapter cable and the load power adapter harness from the PDB. Disconnect all keyed connectors.
    Remove the four screw plugs, then remove ten (10) M4 × 12 Stainless Steel Socket Flange Machine Screws securing the PDB assembly to the cable compartment. Open the cable compartment and remove all harnesses. Release the safety latches on the eight keyed connectors of the PDB, then disconnect the eight power leads (white-to-white, black-to-black). Disconnect the keyed connectors of the battery communication & power harness and the load power adapter harness.
    Remove the battery communication & power harness and the PDB load power adapter harness from the frame. Remove the two ESC signal harnesses (1-to-2) and the two video transmission antennas from the frame. Remove the four power harnesses inside the arms through the center pass-through hole of the frame.
    Remove four (4) M4 × 10 Stainless Steel Socket Flange Machine Screws securing the pre-assembled LiDAR module to the designated upper position on the monocular bracket and remove the LiDAR module.
    Remove the M8 × 20 Stainless Steel Socket Flange Machine Screws from the joint shafts of the four outer arm propulsion assemblies, then remove the joint shafts. Remove the four outer arm propulsion assemblies according to their corresponding positions.
    Remove sixteen (16) M6 × 12 Stainless Steel Socket Head Machine Screws securing the inner joints to the frame.
    Remove the M8 × 25 Stainless Steel Socket Head Machine Screws securing the four inner arm assemblies to the frame. Route the two video transmission antennas back through the frame pass-through holes and out of the inner arm assemblies. Remove the four pre-assembled inner arm assemblies.
    Remove eight (8) M4 × 12 Stainless Steel Socket Head Machine Screws (front and side) securing the PDB cable compartment to the left and right beams and remove the PDB cable compartment.
    Remove the M3 × 20 Stainless Steel Socket Flange Machine Screws securing the video transmission antenna clamps on Inner Arm No. 3 and Inner Arm No. 4 and remove the clamps. Route the two video transmission antennas back through the rear exit holes of Inner Arms No. 3 and No. 4, then remove them through the bottom through-holes.
    Remove the M4 × 14 Stainless Steel Socket Flange Machine Screws securing the joint locking assemblies on the four inner arm assemblies and remove the joint locking assemblies.
    Disconnect the LiDAR wiring harness from the LiDAR.
    Remove four (4) M6 × 8 Stainless Steel Low-Profile Socket Head Machine Screws securing the LiDAR adapter carbon plate to the LiDAR mounting surface and remove the adapter carbon plate.
    (Post-disassembly organization)Classify and store all removed components by type. Clean residual threadlocker and yellow adhesive from component surfaces. Inspect wear items such as screws, connectors and safety latches for integrity and apply identification labels to facilitate subsequent reassembly.

5.5. C31 Lifting Module Disassembly and Assembly

Screw specifications and installation requirements
Title
Title
Title
Title
Serial number
Screw specifications
Screw material number
Torque requirements
1
M5x16
126-000684
4.0±0.4NM
2
M5*14
126-000964
5.0±0.5NM
3
M4*14
126-000749
1.5±0.15NM
4
M5*50
126-000966
1.5±0.15NM
5
M5*16
126-000997
1.5±0.15NM
6
M5*20
126-000965
4.0±0.4NM
7
M4*45
126-000963
1.5±0.15NM
8
M4 lock nut
126-000971
9
M4*12
126-000922
1.0±0.1NM
10
M3*10
126-000283
0.3±0.03NM
11
M3*6
126-000975
0.3±0.03NM
12
M5*20
126-000965
4.0±0.4NM
13
M6*20
126-000968
10.0±1NM
14
M6 lock nut
126-000972
4.0±0.4NM
15
M3*8
126-000631
0.6±0.06NM
16
Φ4*5+M3*L6
126-000887
0.5±0.05NM
17
Φ4*12+M3*L6
126-000970
0.3±0.03NM
18
M3*10
126-000953
0.8±0.08NM

Installation procedure
    Fit the left and right landing gear main beams over the two landing gear bent tubes, respectively. Secure the lifting hooks and the landing gear main beams using sixteen (16) M5 × 16 Stainless Steel Socket Head Machine Screws.Note: Ensure the lifting hooks are oriented outward.After fastening, install eight (8) outer rubber plugs and eight (8) inner rubber plugs to seal the screw holes from the outer and inner sides.
    Secure the two lifting crossbeam side assemblies to the lower side of the lifting hooks using eight (8) M5 × 14 Stainless Steel Socket Flange Machine Screws per assembly. Pay attention to the installation orientation of the side assemblies.
    Insert the four square tube end caps into both ends of the two lifting crossbeam side assemblies.
    Secure the four landing gear clamps to the left and right main beams using two (2) M4 × 14 Stainless Steel Socket Flange Machine Screws per clamp.Note: Ensure the cable clip orientation faces outward, consistent with the lifting hook direction.Then, at the front locating holes of the two landing gear bent tubes, install one searchlight mounting base per side in the specified orientation. Secure each from right to left using two (2) M4 × 14 Stainless Steel Socket Flange Machine Screws.
    Secure the rear upper crossbeam using two (2) M4 × 45 Stainless Steel Socket Flange Machine Screws and two (2) M4 self-locking nuts. Insert two lifting lower crossbeams and one rear upper crossbeam simultaneously into the two lifting crossbeam side assemblies and the main beams.
    Using four (4) tee outer covers, install the front landing gear crossbeam and the rear lower landing gear crossbeam at the designated positions according to the locating holes. Secure each assembly using one (1) M5 × 50 Stainless Steel Socket Flange Machine Screw and four (4) M5 × 16 Stainless Steel Socket Flange Machine Screws.Torque: 1.5 ± 0.15 N·mFinally, from the outer side, secure the crossbeam assembly using four (4) M5 × 20 Stainless Steel Socket Flange Machine Screws.
    Install the two rear radar clamps onto the designated holes of the rear lower crossbeam, ensuring the “UP” marking faces upward. Secure each clamp using one (1) M4 × 14 Stainless Steel Socket Flange Machine Screw and one (1) M4 × 45 Stainless Steel Socket Flange Machine Screw with one (1) M4 self-locking nut.
    Secure the rear radar assembly to the rear lower crossbeam in the orientation shown using four (4) M4 × 12 Stainless Steel Socket Flange Machine Screws.
    Route the searchlight wiring harness around the outside of the landing gear bent tube. Install the searchlight bracket above the searchlight, then secure it to the searchlight mounting base using four (4) M4 × 14 Stainless Steel Socket Flange Machine Screws.
    Install the upper and lower connector mounting bases onto the front crossbeam and secure using three (3) M3 × 10 Stainless Steel Knurled Head Socket Cap Screws.
    Secure the three landing gear searchlight cable clips to the designated positions on the landing gear using three (3) M3 × 10 Stainless Steel Knurled Head Socket Cap Screws.
    According to the locating holes on the crossbeam side assemblies, secure a total of eight (8) HD5150 crossbeam cable clips using eight (8) M3 × 6 Stainless Steel Socket Flange Machine Screws, as shown in the diagram.
    Route the rear radar harness as shown and clip it into the cable clips. Install the rear radar connector dust cap at the connector, then seat it into the upper and lower connector mounting bases. After installing the power connector dust plug and the power connector of the operation main bus, secure them to the designated positions on the connector mounting bases using two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws.
    Secure the lifting anti-sway mounting plate to the lifting lower crossbeam using four (4) M5 × 20 Stainless Steel Socket Flange Machine Screws. Then secure the lifting anti-sway assembly to the mounting plate using four (4) M6 × 20 Stainless Steel Socket Flange Machine Screws and four (4) M6 self-locking nuts.Note: Ensure the load cell wiring harness of the anti-sway assembly faces toward the front side of the landing gear.
    Install the operation main bus end cap into the operation main bus connector, seat it into the upper and lower connector mounting bases and route it together with the searchlight harness as shown. Secure them to the lifting control box using two (2) M3 × 8 Stainless Steel Internal Hex Serrated Flange Screws, then secure the searchlight cable clip and the lifting main bus silicone cable clip using two (2) Φ4 × 5 + M3 × L6 Stainless Steel Shoulder Screws, respectively.
    After routing all harnesses to their specified positions, secure the lifting anti-sway cable clips using six (6) Φ4 × 12 + M3 × L6 Stainless Steel Shoulder Screws.Note: Ensure sufficient slack is reserved for the harnesses on both sides
Disassembly procedure
    Remove six (6) Φ4 × 12 + M3 × L6 Stainless Steel Shoulder Screws from the lifting anti-sway cable clips, release the harness fixation and organize the harnesses.
    Remove the Φ4 × 5 + M3 × L6 Stainless Steel Shoulder Screws from the searchlight cable clip and the lifting main bus silicone cable clip. Then remove two (2) M3 × 8 stainless steel internal hex serrated flange screws from the lifting control box. Remove the operation main bus end cap from the upper and lower connector mounting bases, disconnect the operation main bus connector and organize the searchlight wiring harness.
    Remove four (4) M6 × 20 Stainless Steel Socket Flange Machine Screws securing the lifting anti-sway assembly to the anti-sway mounting plate and remove the anti-sway assembly. Then remove four (4) M5 × 20 Stainless Steel Socket Flange Machine Screws securing the anti-sway mounting plate to the lifting lower crossbeam and remove the mounting plate.
    Remove two (2) M3 × 10 Stainless Steel Socket Flange Machine Screws from the upper and lower connector mounting bases, remove the power cable dust plug and the operation main bus power connector, remove the rear radar connector dust cap and release the rear radar harness from the cable clips.
    Remove the M3 × 10 Stainless Steel Knurled Head Socket Cap Screws from the three landing gear searchlight cable clips and remove the cable clips.
    Remove three (3) M3 × 10 Stainless Steel Knurled Head Socket Cap Screws securing the upper and lower connector mounting bases to the front crossbeam and remove the mounting bases.
    Remove four (4) M4 × 14 Stainless Steel Socket Flange Machine Screws securing the searchlight bracket to the searchlight mounting base, remove the bracket and retract/organize the searchlight wiring harness.
    Remove four (4) M4 × 12 Stainless Steel Socket Flange Machine Screws securing the rear radar assembly to the rear lower crossbeam and remove the rear radar assembly.
    Remove the M4 × 14 and M4 × 45 Stainless Steel Socket Flange Machine Screws from the two rear radar clamps, remove the clamps and store them properly after removal.
    Remove four (4) M5 × 20 Stainless Steel Socket Flange Machine Screws from the outer side of the crossbeam assembly. Then remove the M5 × 50 and M5 × 16 Stainless Steel Socket Flange Machine Screws from the tee outer covers on the front landing gear crossbeam and rear lower landing gear crossbeam. Remove the tee outer covers and separate the crossbeams from the landing gear.
    Remove two (2) M4 × 45 Stainless Steel Socket Flange Machine Screws from the rear upper crossbeam and remove the rear upper crossbeam and the two lifting lower crossbeams.
    Remove two (2) M4 × 14 Stainless Steel Socket Flange Machine Screws from the searchlight mounting bases on the front side of the two landing gear bent tubes and remove the mounting bases. Then remove the M4 × 14 Stainless Steel Socket Flange Machine Screws from the four landing gear clamps and remove the clamps.
    Remove the four square tube end caps from both sides of the two lifting crossbeam side assemblies.
    Remove eight (8) M5 × 14 Stainless Steel Socket Flange Machine Screws securing the two lifting crossbeam side assemblies to the lower side of the lifting hooks and remove the side assemblies.
    Remove the eight (8) outer rubber plugs and eight (8) inner rubber plugs from the screw holes on the left and right landing gear main beams. Remove sixteen (16) M5 × 16 Stainless Steel Socket Head Machine Screws, separate the lifting hooks from the landing gear main beams and remove the left and right landing gear main beams from the two landing gear bent tubes.
    Remove the M3 × 6 Stainless Steel Socket Flange Machine Screws from the eight crossbeam cable clips and remove the cable clips.
    Classify and store all removed components by type. Clean residual contaminants from component surfaces. Inspect wear items such as screws, self-locking nuts and rubber plugs for integrity, apply identification labels and prepare components for subsequent reassembly

5.6. C31 Propeller Clamp Disassembly & Assembly Guide

Screw specifications and installation requirements
Title
Title
Title
Title
Serial number
Screw specifications
Screw material number
Torque requirements
1
M10*20
126-000871
Blade pull 0.4-0.5 kgf
2
M3*10
126-000953
0.8±0.08NM
Installation procedure
    Each arm consists of two propulsion sets (upper and lower).
    The upper propeller must match the motor rotation direction (both CW or both CCW) and the printed side of the propeller must face upward.
    The lower propeller on the same arm must also have the printed side facing upward and its rotation direction must correspond to the motor as follows:
    If the lower motor is CW, the propeller must be CCW, printed side facing upward.
    If the lower motor is CCW, the propeller must be CW, printed side facing upward.
    Ensure the propellers are installed in the correct CW/CCW orientation corresponding to the motors. The shim (spacer) assembly of the lower propulsion set is installed in a mirror-symmetric configuration relative to the upper set.
    Apply threadlocker to approximately one-third (1/3) of the length of each M10 × 20 hex socket screw, then apply one drop of threadlocker at two opposite positions at the entrance of the threaded hole.Secure the upper propeller clamp, then perform a pull-force test to verify compliance: 0.4–0.5 kgf. Conduct a flight test within 2 hours and after completion, perform the pull-force test again.
    Note:The pull point of the force gauge must be approximately 8 cm from the propeller tip.
    Test Method:
    Use one hand to hold the motor firmly, preventing movement or rotation.
    Use the other hand to pull the propeller steadily with the force gauge.
    Record the force value while the propeller is moving at a constant speed: 0.4–0.5 kgf.
    Both propellers in one set must fall within the specified range.
    Secure the lower nose outer cover to the main beam using six (6) M3 × 10 Stainless Steel Socket Flange Machine Screws.
    Secure the upper nose outer cover to the main beam using six (6) M3 × 10 Stainless Steel Socket Flange Machine Screws.
    Secure the front nose outer cover to the upper and lower nose covers using six (6) M3 × 10 Stainless Steel Socket Flange Machine Screws
Disassembly procedure
    Remove sixteen (16) M10 × 20 hex socket screws from the propeller clamps, then remove the propeller clamps, propellers and shims.
    Remove six (6) M3 × 10 Stainless Steel Socket Flange Machine Screws and remove the front nose outer cover.
    Remove six (6) M3 × 10 Stainless Steel Socket Flange Machine Screws and remove the upper nose outer cover.
    Remove six (6) M3 × 10 Stainless Steel Socket Flange Machine Screws and remove the lower nose outer cover.