Software Management Control in Aviation

Software Management Control (5.13) Learning Objectives

• Describe the restrictions that apply to software management and control (Level 2).
• Describe the airworthiness requirements for software management and control (Level 2).
• Describe the possible catastrophic effects of unapproved changes to software programs (Level 2).

Aircraft Software Use

• Software is used to program information for computers in aircraft systems.
• Includes components such as engine control systems, bleed air control systems, power generation and control systems, fire protection systems, and aircraft instrument displays.
• Modern aircraft rely extensively on computer software to control navigation and flight management systems.
• Continual software updates are necessary due to ongoing changes in navigation requirements.
• Changes may result from airline route changes, air traffic control adjustments, or shifts in waypoints.

Built-In Test Equipment (BITE)

• Aircraft use BITE to communicate with other systems to test and identify issues.
• BITE is a programmed system.

Multifunction Control Display Unit (MCDU)

• MCDUs are programmed using software that communicates with multiple systems.
• Used to update or input data, test and detect faults.

Software Control Levels

• Each aircraft component and system with software is assigned a software level.
• Severity of potential software errors affects the level, impacting aircraft safety and occupant consequences.
• Software levels are assigned per guidelines in DO-178C.
• The document is jointly prepared by RTCA SC-167 (Radio Technical Commission for Aeronautics safety critical working group) and EUROCAE WG-12 (European Organisation for Civil Aviation Equipment).
• Airborne software is either aircraft-controlled or hardware-controlled.
• Loadable software may be categorized as either aircraft-controlled or hardware-controlled, and include aircraft-controlled loadable software parts (ACLSP), hardware-controlled loadable software parts (HCLSP), loadable software aircraft part (LSAP), resident software (RS), or preloaded software, and aeronautical databases (ADB).
• Software levels are categorized by potential effect on aircraft operations, and include catastrophic, hazardous, major, minor and no effect.

Flight Software Design Assurance

• Software design is treated like aircraft components for certification and procedural purposes.
• Catastrophic failure levels include flight control computers, flight displays, and air data systems.
• Hazards include Autopilot, autothrottle, ice protection, standby flight displays, ILS, and landing gear control.
• Major failures may involve navigational systems, yaw damper, and environmental control systems, among others.
• Minor system failures include flight data recorders and cabin lighting.
• Systems with minimal effect include in-flight entertainment, among others.

Software Types

• Two primary types: field-loadable software (FLS) and preloaded or resident software.
• FLS: independently loadable by maintenance personnel, with an unique part number and verifiable in-aircraft hardware memory.
• Preloaded/resident: requires removal and physical changes at a workshop.

Field-Loadable Software (FLS)

• FLS is software, including data tables, which can be quickly loaded onto aircraft by personnel, without removing the system.
• FLS has a unique part number and can be verified on the aircraft.
• FLS does not change the target hardware part number.
• It can be updated regardless of the current software state.

Preloaded/Resident Software

• Cannot be changed on the aircraft requiring a workshop environment for updates.
• Some aircraft components or computers may not have software changes needing updates for a prolonged period.
• Loadable software is not an option if the component is located in an inaccessible area.

Loadable Software Aircraft Part (LSAP)

• LSAP is software considered part of the aircraft's certified design, requiring release documentation.

Non-Loadable Software Aircraft Part or Aeronautical Database

• These are not part of the certified aircraft design, but may be routinely updated without formal modification approval.
• Navigation and flight planning, among other applications, depend on these types of parts.
• Critical to configuration control, although not part of the Type Certificate.

Databases

• Model/Engine Databases (MEDB): customized, performance-based databases.
• Aeronautical Databases (ADB): typically updated periodically and provide navigation and routing data.

Operator Modifiable Software (OMS)

• OMS allows operators to modify systems for preferred procedures or local conditions.
• It includes User Modifiable Software (UMS) and User-Certifiable Software (UCS).
• Modifications involve data and code changes affecting systems such as ACARS, ACMS, SATCOM, and IFE systems.

User Certifiable Software (UCS)

• Software that operators modify under specific guidelines acceptable to the regulatory authority.

Supplier Controlled Software

• Operational Program Software (OPS), software instructions for line replaceable units (LRUs).
• Each version of OPS has a unique part number.

Operational Program Configuration (OPC)

• OPC determines the function of a Line Replaceable Unit (LRU), including enabling or disabling functions.

Aircraft Configuration List (ACL)

• A list of modules and LRUs for specific aircraft types.
• Found in drawings, service bulletins, service letters, and illustrated parts catalogs, or separate tracking systems.

Software Media

• Software media transports and distributes software, including discs, memory cards, tapes or internet.

Software Version

• Software versions are identified by major, minor and patch version numbers, often denoted as A.BB where A is the major and BB is the minor version.
• Crucial for managing software updates.

Target Hardware

• Identifies the hardware components (LRUs or modules), utilized for loading new FLS.
• Target components include EGPWS, Flight Control Computer (FCC), and Flight Management Computer (FMC).
• Hardware databases include systems for navigational and maneuvering tasks.

Sourcing Software

• Updates are acquired from acceptable sources like the Target Hardware Manufacturer.
• Necessary documentation should include media, identification, and quality/conformity markings.

Software Data Loading & Data Loaders

• Data loaders (ADLs or PDLs) transfer software updates to programmable systems, typically used for systems that are not part of a ROM, PROM or EPROM type system.
• Data loaders are needed to ensure that modifications, and the required software and data, can be effectively downloaded.

Portable Maintenance Access Terminal (PMAT)

• PMATs are used for quick software data transfer to the aircraft.
• This allows either 3.5-in. disks or CD-ROMs to be utilized for data transport .

FLS Loading and Certification

• Loading FLS is done via PDL, ADL or an off-aircraft data loader.
• Certification must be handled via procedures outlined by appropriate maintenance manuals, and by keeping relevant configuration and maintenance records.
• Certification releases are handled by authorized personnel/teams.

Electronic Distribution of Software (EDS)

• EDS distributes FLS from suppliers or manufacturers to a remote site, avoiding physical media needs.
• Electronic distribution should adhere to standards acceptable to the regulatory authority, with confirmation of the changes made.

Field-Loadable Software Procurement and Documentation

• LSAP is delivered with equipment and kept in binders or storage areas.
• LSAP procurement sources and documentation must adhere to acceptable guidelines (e.g., JAA forms or FAA 8130-3).

FLS Storage Media Handling

• Software media should correctly be treated, to ensure media life preservation.
• Storage media must be sealed and labeled.
• Physical/environmental conditions like moisture, dust, sunlight or electromagnetic exposure must be avoided.

Replication of FLS

• Aircraft Type Design Organisation processes must be used for FLS copies.

Procedures & Maintenance Management Exposition (MME)

• Operators must have documented procedures concerning software procurement, distribution, verification, embodiment, testing, release and audit.
• These procedures should adhere to maintenance and management exposition (MME) specifications or equivalent methods for compliance.
• Aircraft software alteration can change aircraft performance. Systems affected may include engine, navigational, and flight controls.

This quiz covers essential aspects of software management and control within aircraft systems. You will learn about restrictions, airworthiness requirements, and the significant risks associated with unapproved changes to software. Understand the role of software in critical aircraft functions and the importance of continuous updates for safety and compliance.