Educational familiarization only. This is original TechOpsBase learning content created from privately supplied legacy training and MSG-3 source material. It does not reproduce manufacturer pages, proprietary diagrams, task steps, numerical maintenance limits, dispatch criteria or controlled maintenance data. Current approved aircraft data, effectivity and operator procedures govern all aircraft work.
Resource profile
- Aircraft: Airbus A350 family
- ATA chapter: 42 — Integrated Modular Avionics
- Resource: A350 ATA 42 CPIOM H41 and H42
- Level: Intermediate-to-advanced
- Status: Draft pending technical review
Learning objectives
- Identify H41/H42 as Type-H CPIOMs.
- Understand paired/common-resource reasoning.
- Interpret total-module and interface losses.
- Use hosted-application allocation.
- Diagnose module versus network faults.
1. Purpose and operational value
CPIOM H41 and H42 are paired Type-H common resources whose loss can affect their allocated applications and interface channels.
2. Architecture and system flow
H41 and H42 share the general CPIOM hardware/software architecture but have effectivity-specific application allocation and physical interfaces.
Their loss must be interpreted by the functions hosted in each module and by the remaining redundant or alternate application path.
The MSG-3 failure matrix distinguishes total CPIOM loss from loss of AFDX, ARINC 429 or CAN interface groups.
3. Major components and functions
H41 CPIOM
Hosts assigned applications and I/O. The component must receive the correct input, perform its intended function and provide a valid output or status. A maintenance diagnosis must separate loss of power, loss of communication, incorrect configuration, blockage or leakage, contamination, mechanical degradation and an upstream or downstream interface failure. Useful evidence includes power, module health, hosted functions and interfaces. Command, feedback and physical effect must agree before hardware is condemned.
H42 CPIOM
Provides paired or complementary common resources. The component must receive the correct input, perform its intended function and provide a valid output or status. A maintenance diagnosis must separate loss of power, loss of communication, incorrect configuration, blockage or leakage, contamination, mechanical degradation and an upstream or downstream interface failure. Useful evidence includes same evidence with comparison to H41. Command, feedback and physical effect must agree before hardware is condemned.
AFDX interfaces
Exchange network data. The component must receive the correct input, perform its intended function and provide a valid output or status. A maintenance diagnosis must separate loss of power, loss of communication, incorrect configuration, blockage or leakage, contamination, mechanical degradation and an upstream or downstream interface failure. Useful evidence includes A/B link, end-system and virtual-link status. Command, feedback and physical effect must agree before hardware is condemned.
A429/CAN interfaces
Connect non-AFDX equipment or gateways. The component must receive the correct input, perform its intended function and provide a valid output or status. A maintenance diagnosis must separate loss of power, loss of communication, incorrect configuration, blockage or leakage, contamination, mechanical degradation and an upstream or downstream interface failure. Useful evidence includes channel-group loss and affected subscribers. Command, feedback and physical effect must agree before hardware is condemned.
Power supply
Supports module availability. The component must receive the correct input, perform its intended function and provide a valid output or status. A maintenance diagnosis must separate loss of power, loss of communication, incorrect configuration, blockage or leakage, contamination, mechanical degradation and an upstream or downstream interface failure. Useful evidence includes source, protection, voltage and intermittent history. Command, feedback and physical effect must agree before hardware is condemned.
4. Normal operating sequence
1. Power-up
Each module initializes and reports health.
2. Application start
Assigned partitions become available.
3. Data exchange
AFDX and local interfaces carry required data.
4. Failure
FWS/CMS reflects affected applications and common-resource cause.
5. Control, monitoring and protection
Do not assume H41 and H42 are interchangeable without approved configuration and allocation data.
A total module loss and a total interface-group loss can produce different affected-function patterns.
6. Failure modes and maintenance reasoning
- Total H41 loss: All hosted applications/interfaces on H41 affected.
- Total H42 loss: All hosted applications/interfaces on H42 affected.
- All AFDX data lost: Module end-system/interface path.
- All A429/CAN lost: Specific I/O-group or hardware fault.
- Intermittent module reset: Power, thermal, hardware or software.
7. Interfaces with other aircraft systems
- Hosted aircraft systems.
- AFDX switches/network.
- CRDCs and direct non-AFDX users.
- FWS/CMS.
- Electrical/cooling.
8. Practical maintenance scenarios
H41 apps lost, H42 healthy
Use common H41 power/module evidence.
Only CAN-connected functions lost
Localize the interface group, not complete module.
Multiple ECAMs plus IMA root-cause line
Correlate to hosted application list.
9. Technician takeaways
- Use exact module/application allocation.
- Interface-group failure is not total module failure.
- Compare H41/H42 state.
- Configuration control is mandatory.
Maintenance boundary
This resource explains architecture, operation, indications and system-level troubleshooting. It intentionally excludes removal/installation instructions, wiring-pin checks, maintenance limits, software part numbers, servicing quantities, inspection intervals and release-to-service criteria.
Review prompts
- What is the required system function?
- Which component commands, processes or physically performs it?
- Which power, fluid, pneumatic or data path is required?
- What command proves the function was requested?
- What feedback or physical effect proves correct operation?
- Which adjacent ATA system can create the same symptom?
- What evidence should be preserved before reset, draining, servicing or software action?
- What hygiene, electrical, pressure, network or safety boundary applies?
