Airbus Industry & it's usage of IVHM
Information on IVHM systems are essential for the OEM and therefore to a high degree kept confidential. Due to the limited access to open source information and restrictions for disclosing internal date the following overview is neither complete nor validated. Obviously, the complexity and maturity of the systems increases with later entry into service. Especially for the Airbus A380, A400M and A350 an evolution in the maintenance systems can be seen.
The availability and reliability of an aircraft, together with the cost optimization – in this case maintenance cost - are the most important goals of commercial airlines. To reach these goals an integrated vehicle health management should give the opportunity to optimize the maintenance schedule with full availability of the aircraft.
Current status of IVHM in European Air Vehicles
The literature research on Integrated Vehicle Health Management systems in European Aircrafts shows that at present none of the most advanced A/C does feature a complete, fully-integrated IVHM system. However, especially on the three different Airbus aircraft A380, A400M and A350 an evolution of IVHM can be seen. Also differences in the approach to IVHM for military and civil A/C can be found as shown in table Error! Reference source not found.. For civil aviation instant information of a system failure is needed to trigger maintenance and logistic while the A/C is still airborne in order to keep ground time at a minimum and stay within the flight schedule.
The fatigue usage between civil and military A/C is very different. For civil A/C a forecast on the fatigue usage can be done by flight hours and flight cycle consumption. On military A/C the type of mission is very relevant for the fatigue consumption. Logistical missions are comparable with civil aviation. On training and tactical missions the fatigue consumption depends on the mission and is usually higher than on logistic missions. Therefore a precise load monitoring system is needed.
Function of Structural Health Management (SHM) in Eurofighter Typhoon
Structural-Health-Monitoring plays an important role in the life time of a military aircraft. In contrast to a commercial aircraft the missions and therefore the loads are changing more extreme and more frequent. Using a SHM allows to predict the remaining life time more precise and therefore increase the structural safety as well as the economic use of the aircraft vehicle. A fatigue consumption study on the structure of a C-160 Transall military transport A/C shows that the different mission types logistic, tactical, and training have different impacts on the fatigue consumption. The logistic mission can be assumed to be similar to the usage of commercial A/C. The main fatigue consumptions occur during tactical and training missions.
Functioning of IVHM in Airbus A400M
The Airbus A400M Atlas is a military transport aircraft designed from Airbus Defence and Space (DS). The A400M is a four engine driven turbo-prop aircraft. The first flight of the A400M was in December 2009 and the EIS was in August 2013.
For the development of the avionics of the A400M Airbus DS uses the experience of Airbus gathered with the development of the A380. For that reason Integrated Modular Avionics (IMA) are used in the A400M to enable an Aircraft Integrated Monitoring and Diagnostic System (AIMDS). The IMA provides the interconnection between the different systems and functions for an easier data transfer between the systems and to the AIMDS.
Integrated Vehicle Health Management in Air Vehicles
The following section presents an overview on the development of health management in aircraft with special consideration of Airbus and Boeing as the biggest aircraft manufacturers and a summary of approaches from other Original Equipment Manufacturer OEMs such as Embraer, Bombardier and engine manufacturers.
Health Management on-board of aircraft is not a new idea (Aircraft Commerce, 2006) describes the evolution of on-board maintenance computers: In the beginnings, problems announced by PIREPs and technical logs were analyzed using Fault Isolation and Trouble Shooting Manuals. The introduction of “push-to-test” equipment on the B727 for mechanical and analog systems initiated further Built-In Tests (BIT), Fault Report Manuals and Line Replaceable Units (LRU) with Built-In Test Equipment (BITE). The A310 used a central display for the Engine Indicating and Crew Alerting System (EICAS) and the A320 had the Centralized Fault Display System (CFDS) installed which accommodates a Multi-function Control Display Unit (MCDU) with the Aircraft Communications Addressing and Reporting System (ACARS) for communication between aircraft (A/C) and a network of radio trans-receivers on ground. The B747-400 introduced the centralized maintenance system (CMS). The results of the data analysis conducted by the Centralized Maintenance Computer (CMC) are displayed on the Common Display Unit (CDU).
Maintenance workflow of A380 fitted with IVHM
The Airbus A380 is a four engine driven large airplane with 2 passenger decks. The first flight was in April 2005 and entry into service (EIS) was in October 2007. Until February 2015 317 A380 have been ordered. 154 aircraft have been delivered and are in operation. The largest operator is Emirates Airlines with 59 aircraft.
The A380 is equipped with a new maintenance system architecture compared to the previous Airbus aircraft types. It consists of:
• Onboard Maintenance Terminal (OMT)
• Portable Multipurpose Access Terminal
• Digital Cabin Logbook (DCL)
• Onboard Maintenance System (OMS)
• Centralized Maintenance System (CMS)
• Aircraft Condition Monitoring System (ACMS)
• Power Distribution Control System (PDCS)
• Data Loading and Configuration System (DLCS)
The OMT is a computer working space installed in the cockpit of the A380 to enable access to the software applications which are installed in the OMS.
Operation of Health & Usage Monitoring System (HUMS) in Dassault Rafale
The Dassault Rafale is a twin-engine multirole fighter aircraft which had the first flight in July 1986 and the EIS in May 2001. The fighter is designed and built by Dassault Aviation.
The HUMS of the Rafale is equipped with an A/C Mission Computer (ref. to Fig. Error! No text of specified style in document.-1) which monitors real time peak-to-peak values of a steering parameter. If the steering parameters exceed pre-determined values the parameters get recorded on the Mass Memory Cartridge (MMC). Also static exceedances on critical areas based on a static operator database are recorded.
Prognostic Health Management (PHM) of Saab Gripen
The Saab JAS 39 Gripen is a Swedish multirole fighter aircraft. The single engine A/C was designed for the Swedish Air Force and is operated by six different nations up to now. The first flight of the Gripen was in December 1988 and the EIS was in November 1997.
The PHM system of the Gripen consists of aircraft and ground functions. The aircraft functions are:
• Safety Check (SC)
• Functional Monitoring (FM)
• Fault Reports (FRPT)
• Fault Isolation (FI)
• Functional Check (FC)
• Maintenance Data Recording (MDR)
Research activities on Integrated Vehicle Health Management in European Air Vehicles
In Europe there are several research projects dealing with IVHM. Here we have given a short introduction about three different projects which have been or will be carried out in Europe.
TATEM was an EU financed maintenance project to reduce the cost of maintenance. TATEM stands for Technologies and Techniques for New Maintenance Concepts. The consortium was build up by 58 contributors from 12 European countries under the lead of Smiths Aerospace Electronic Systems, Cheltenham.
OMAHA is a project promoted within the German funded aeronautic research program V with a runtime from January 2014 to March 2017. OMAHA is the acronym for Overall Management Architecture for Health Analysis. The project objective is a holistic CBM approach for civil aircraft.
• Clean Sky 2
Clean Sky is a public private partnership between the European Commission and the aeronautical industry. Clean Sky 2 is supposed to deliver break-through technologies for incorporation into the next generations of aircraft from 2025 onwards.
Technologies in Aircraft Structural Health Monitoring
Structural Health Management (SHM) is defined by (Speckmann H. R., 2006) as “continuous, autonomous in-service monitoring of physical condition of structure by embedded or attached sensors with minimum manual intervention, to monitor structural integrity of aircraft”. Parameters that have to be monitored in airframe and structural components for service life degradation or necessary maintenance actions are e.g. crack growth, corrosion, flight loads, and stresses. Prognostic Health Management (PHM) for airframe structures aims at real-time load monitoring and quantifiable damage identification and estimation (location and size) on global structural level. Furthermore a precise damage diagnostics on local level including an automated reasoning and decision making module is targeted.
Technologies in Aircraft System Health Monitoring
Various kinds of health monitoring technologies for systems are described in the literature. Valve condition monitoring or automated switch test equipment are examples. Due to the differences in design and functionalities, the range of possible technologies is very diverse. Failure modes (e.g. clogging of electro-hydraulic servo-valve output) comprise electrical, mechanical and hydraulic components and can be disguised by aerodynamic loads and other varying forces which makes the fault detection and failure prediction a complex task (Bizzaria, 2009). Commonly used devices in ISHM are vibration, temperature, flow, position, pressure or current sensors. Many systems are already equipped with sensors, power and data transfer devices. Therefore, the IVHM approach can be performed without additional equipment installation. Depending on the application, different performance indicators such as capacity and voltage for batteries or pressure differences for hydraulics have to be monitored. The RUL distribution can be calculated based on future operating conditions (loads) and the associated failure thresholds
Vehicle Health Management of A350
The Airbus A350 is the newest aircraft in the Airbus Family. The first flight was in June 2013 and entry into service was in January 2015. The A350 is the first Airbus aircraft with a fuselage made of carbon fiber. The A350 is designed in accordance with the Extended-range Twin-engine Operational Performance Standards.
The On-board Maintenance System of the A350 is a further development of the OMS of the A380. The OMS establishes the logical links between all the different applications. If a failure occurs which effects the flight-, cabin or maintenance-operation a maintenance message is triggered. The information will be displayed at the Electronic Centralized Aircraft Monitoring (ECAM) or - if the cabin is effected - on the Flight Attendant Panel (FAP).