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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR5992 AEROSPACE INFORMATION REPORT AIR5992 Issued 2009-11 Reaffirmed 2015-10 De
5、scriptions of Systems Integration Test Rigs (Iron Birds) For Aerospace Applications RATIONALE AIR5992 has been reaffirmed to comply with the SAE five-year review policy. TABLE OF CONTENTS 1. SCOPE 3 1.1 Purpose . 3 2. APPLICABLE DOCUMENTS 3 2.1 Applicable Documents 3 2.1.1 SAE Publications . 3 2.1.2
6、 U.S. Government Publications 3 2.1.3 Other Publications . 4 3. BACKGROUND 4 3.1 Types of Testing Performed on Systems Integration Test Rigs . 5 3.1.1 Hydraulic System Integration 6 3.1.2 Electrical System Integration 7 3.1.3 Open Loop Flight Control Integration 7 3.1.4 Closed Loop Flight Control In
7、tegration (Pilot-in-the-Loop) . 9 3.1.5 Utility System Testing 10 3.1.6 Crew Training 10 3.1.7 Maintenance Training . 10 3.1.8 Engineering Investigations 10 3.2 Systems Represented on Test Rigs . 10 3.2.1 Hydraulic Systems 12 3.2.2 Electrical Systems . 12 3.2.3 Mechanical Systems . 12 3.2.4 Flight C
8、ontrol Systems 12 3.3 Systems Integration Test Rig Structure 13 3.4 Test Rig Control Surface Representation . 14 3.4.1 Surface Inertia . 14 3.4.2 Airloads . 14 3.4.3 Stiffness 14 4. DESCRIPTIONS OF MILITARY SYSTEMS INTEGRATION RIGS . 15 4.1 Bombers 15 4.1.1 Northrop Grumman B-2 Flight Control and Hy
9、draulic Integration Laboratory (FCHIL) 15 4.2 Fighters . 19 4.2.1 McDonnell Douglas F-15E / SMTD Integration Test Rig Description . 19 4.3 Trainiers 29 4.3.1 Alenia Aermacchi M346 Flight Control, Landing Gear General Specification For 2.1.2 U.S. Government Publications Available from the Doucment Au
10、tomation and Production Service (DAPS), Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094, Tel: 215-697-6257, http:/assist.daps.dla.mil/quicksearch/. MIL-STD-810F Environmental Engineering Considerations and Laboratory Tests MIL-HDBK-831 Preparation of Test Reports SAE INTERNATIONAL AIR59
11、92 3 OF 64MIL-HDBK-2165 Testability Handbook for Systems and Equipment MIL-STD-5522 Test Requirements and Methods for Aircraft Hydraulic and Emergency Pneumatic Systems MIL-H-8891A Hydraulic Systems, Manned Flight Vehicles, Type III Design, Installation but also simulated the control surface stiffne
12、ss, moment of inertia, air loads, and even aerodynamic damping. With the advent of high authority redundant control augmentation systems (CAS), fly-by-wire technology (FBW), and vehicle management systems (VMS) the Iron Bird has evolved into more of a system integration facility. There is no questio
13、n that the Iron Bird facility has been critical to the development and advancement of flight control systems since the inception of powered systems. The Iron Bird is considered an aircraft flight control and subsystems mockup because it dynamically duplicates the flight control system and supporting
14、 subsystems with preproduction/production components as installed on the aircraft. An extensive array of equipment from each of the major aircraft subsystems is used to build the Iron Bird facility. Typically Iron Birds have included: flight critical aircraft computers; flight control actuators and
15、valves; utility actuators and valves; a limited cockpit/crew station sufficient to assess functional responses and failure transients (stick/pedals/throttle/displays); an electrical system and wiring; a six-degree-of-freedom airframe and engine dynamic simulation; motor driven hydraulic pumps, hydra
16、ulic reservoirs, lines and fittings, heat exchangers and filter manifolds; components in spatially correct locations; simulated surface installations; and extensive test instrumentation and data recording capability. Iron Birds can also have other utility systems installed on them, for example; land
17、ing gear systems, cargo/bomb door actuation, and hydraulically powered electrical generators. The major benefit of including an Iron Bird facility in an airplane systems development and validation program is technical and schedule risk reduction. Typically an Iron Bird can be completed and populated
18、 with aircraft hardware or aircraft-like hardware as much as one year prior to integration testing on the first aircraft. If a problem is discovered prior to the system installation on the aircraft it will obviously be less costly to correct than if the problem were discovered on the aircraft. There
19、 is always more flexibility in the program schedule prior to aircraft roll out than there is afterward. To assess the benefits of finding problems early, experience is often relied on, but history from previous programs within the company can also be quantified, as can the costs associated with prog
20、ram delays at different points in the system development. New systems or more integrated systems lead to more risk than the testing of mature technologies. It should also be noted that the Iron Bird also has the advantage that the facility itself is much more accessible and easier to work on than an
21、 actual aircraft. This accessibility is also important when considering the cost associated with investigating and correcting system problems. On military programs Iron Bird requirements are defined in government and industry standards (AS94900, AS5440, and MIL-STD-5522). On commercial programs comp
22、any processes, experience and FAA regulations determine the use of an Iron Bird. Often the decision to develop an Iron Bird facility is dictated by corporate culture, history, and experience. With the maturing of many flight control technologies and the improvement of many analytical techniques, the
23、 traditional uses for an Iron Bird facility are beginning to be reassessed. The cost associated with developing an Iron Bird must be carefully considered in light of the necessity to control the costs associated with new aircraft development. Some contractors SAE INTERNATIONAL AIR5992 4 OF 64believe
24、 that for prototype programs the aircraft can be used as its own Iron Bird, augmented by less sophisticated test benches and hydraulic checkout facilities to fulfill the integration test requirements at a reduced cost. The use of an Iron Bird is often evolving within a company and different companie
25、s tend to use Iron Birds differently. This AIR will attempt to provide the pros and cons of these various approaches so that readers will be able to better determine how they may take advantage of an Iron Bird facility. 3.1 Types of Testing Performed on Systems Integration Test Rigs Determining the
26、scope of testing that will be accomplished on an Iron Bird is essential in deriving the requirements for the facility. The scope of the testing must be determined using a disciplined systems engineering approach to determine system requirements and to determine how these requirements will be validat
27、ed. Each individual requirement must be reviewed and a determination made regarding how and where to validate each of these requirements. The Iron Bird test plan should document the required tests and the expected results. For each requirement that has to be verified by test, the question needs to b
28、e considered where the requirement would be validated if not on an Iron Bird. Again, this often means that the test will have to be performed on the aircraft. The risk of performing a particular test on the aircraft has to be considered carefully as there are often constraints on an aircraft that ar
29、e not a factor on an Iron Bird. The Iron Bird often has more data capturing capability than an aircraft since there are no volume or power constraints on the instrumentation system. The accessibility of an Iron Bird is often a great benefit especially considering the ease in which failures can be in
30、serted and tested without the risk of damaging the aircraft. A decision to use the Iron Bird facility for certification activities can significantly impact its manufacture This has not typically been done in military programs and many commercial aircraft manufacturers also treat the facility as an e
31、ngineering integration and test facility. However, some commercial companies have recently investigated using the Iron Bird for formal certification. In general, anything that the responsible FAA specialist can be convinced is representative of the airplane can be used for certification. In order to
32、 get credit for certification, the test article must have FAA conformity, which requires released drawings, material and configuration control, and an FAA inspector to verify that all the parts are actually built per the drawings. The desire to use the Iron Bird for certification should be carefully
33、 considered versus the cost of certifying these items with aircraft testing or other test facilities. It can easily be argued that the greatest benefit of an Iron Bird facility is derived while preparing the test facility to begin the formal testing. This will be where many integration problems will
34、 be discovered. Experience shows that although some problems are discovered once formal testing has started; the majority of the problems will be discovered by accident. Test plans are written based on past experience and knowledge of the most likely “unknowns”. These are often referred to as the “k
35、nown unknowns” and are items that are usually accommodated in the design to begin with. Of greater concern is what is referred to as “unknown unknowns”. These are often discovered during functional check out and preparation for tests that will be performed during the course of the formal testing. Th
36、ese types of problems underscore the necessity of having a test team familiar with the system being tested. There must be a disciplined process for verifying expected results and documenting unexpected results or an “anomaly”. It is often the test teams investigation of an unanticipated characterist
37、ic or an anomaly that leads to discovering problems with the system often the characteristic was not related to the system being tested. It is therefore essential that the test team is very familiar with the system and that adequate time be provided for investigation of anomalies, suspected problems
38、, and regression testing. Also, the test plan should include a period of time for “stress testing” which consists of unstructured tests intended to assess the robustness of system design. The scope of testing which must be performed on an Iron Bird will be uniquely tailored for each aircraft program
39、. The required testing will be dependent on many factors, such as: The aircraft and systems design The aircraft development schedule Experience with similar certified systems Testing that can be or has been adequately performed in lower cost facilities, etc. SAE INTERNATIONAL AIR5992 5 OF 64The emph
40、asis of the next sections is on providing examples of testing that has typically been performed in the Iron Bird facility 3.1.1 Hydraulic System Integration The Iron Bird allows the testing of complex aircraft hydraulic systems that have only relatively recently been successfully modeled. The bulk o
41、f the hydraulic system testing is accomplished in conjunction with the flight control integration testing described in the following sections. Many of these tests are described in more detail in the specifications listed in Section 3.2. The types of testing considered for Hydraulic Integration are s
42、ummarized below. 3.1.1.1 Hydraulic System Functional Testing Initial testing on an Iron Bird typically consists of system functional testing. The emphasis of this testing is functional checkout of the system and ensuring that all the components in the system will work together. The testing also cons
43、ists of assessing the system and confirming that it is performing per the analytical predictions. Once the system appears to be operating correctly, additional testing is performed to further quantify system performance. 3.1.1.2 Hydraulic System Demand Hydraulic demand and pump sizing are often asse
44、ssed on the Iron Bird. In order to perform this testing a closed loop simulation is desired and is used to provide realistic aircraft component usage. This could be approximated open loop, but is much more representative of what will be observed in flight if an aerodynamic model is available. The fl
45、ight controls and flying qualities teams need to consult with the hydraulic system designers to determine where in the flight envelope the power requirements of the control surfaces coupled with other utilities most challenge the hydraulic power available. Typically this will be a slow speed regime
46、where power settings are low and control activity is high. For some aircraft this could be the approach phase when flaps are being extended and the gear are being lowered, coupled with high control surface usage. For tactical aircraft, a spin or departure is often the cause of the highest control su
47、rface usage but it could also be a carrier landing or aggressive maneuvering while using a high flow utility such as a gun. 3.1.1.3 Hydraulic System Pressure Drop Pressure drop testing is often used to verify that the pressure drops throughout the system meet the predictions of the modeling techniqu
48、es used in recent years to design hydraulic systems. Pressure drop data is essential to ensure that actuators will achieve their specified loaded rate performance and that pumps will not cavitate. 3.1.1.4 Hydraulic Water Hammer Water hammer or pressure surge testing is often performed on an Iron Bir
49、d; however, the desire to accomplish this testing will require that the Iron Bird accurately represent the aircraft hydraulic system. Flight hardware or a very close facsimile is necessary as this phenomenon is very dependent on the actual layout of the hydraulic system. 3.1.1.5 Hydraulic Pump Ripple Hydraulic pump ripple testing is also conveniently accomplished on an Iron Bird. The plumbing and support brackets around
