Aerospace Ground Equipment Research Articles

SPIRET: An Innovative Technique for Random Vibration Testing Of Large Spacecraft

Abstract System Point Input Random Excitation Testing (SPIRET) was developed as an alternative to both system level acoustics and base-shake random vibration testing of large spacecraft. The goal of SPIRET was to obtain an enhanced workmanship test of the spacecraft, prior to launch, by inducing a higher, more uniform dynamic acceleration response throughout the integrated system. The underlying SPIRET concept is to utilize the spacecraft modal characteristics to amplify the shaker input force and produce a high acceleration response throughout the flexible structure. SPIRET utilized commercial off-the-shelf vibration equipment coupled with satellite specific Mechanical Aerospace Ground Equipment (MAGE). Random vibration control was achieved using inline load cells and a Force Spectral Density (FSD) input spectrum which effectively provided both feedback control of the shaker and force limiting during the vibration test. SPIRET effectiveness was verified using a hi-fidelity spacecraft simulator which was previously used for structural and acoustic testing. This enabled direct comparison of SPIRET response accelerations to acoustic response accelerations at common spacecraft locations. In general, SPIRET produced higher dynamic loading throughout the spacecraft than did acoustic testing at Protoqual (PQ) levels over the tested frequency range of 5Hz to 500 Hz. This resulted in a more thorough workmanship screen of the spacecraft prior to launch. The benefits of SPIRET extend beyond the technical goal of achieving an enhanced system workmanship test. Significant schedule and cost savings were realized since the test was conducted within the spacecraft final assembly facility which enabled parallel vehicle processing activities and shared personnel resources. SPIRET has been successfully used as the final integrated spacecraft level dynamic test at Lockheed Martin Denver since 2001.

A Methodology to Reduce Aerospace Ground Equipment Requirements for an Air Expeditionary Force

For many years the US military has maintained a significant overseas presence. Changes in the international political landscape has led to military reductions, particularly in this overseas military presence. To meet increased deployment demands from US-based stations the US Air Force is restructuring to accommodate an Expeditionary Aerospace Force (EAF) concept. As the United States Air Force evolves into an EAF using tailored combat force packages to meet specific threats, the requisite support functions for the deployed forces will garner increasing attention. We propose and examine a simulation-based methodology for examining options to reduce the amount of support equipment deployed with a tailored force. The simulation model is based on aircraft system failures and the ensuing maintenance actions. These maintenance actions drive the utilisation of aerospace ground equipment used to support aircraft maintenance. Support equipment deployment levels are re-examined using expected equipment utilisation rates while the risk to combat capability is quantified. Specific deployment support options examined include maintenance restrictions, just-in-time delivery of support equipment and the potential impact of proposed consolidated, or multifunction support equipment. Impacts on airlift requirements are estimated for each strategy examined.

Real-Time and Integrated Measurement of Potential Human Exposure to Particle-Bound Polycyclic Aromatic Hydrocarbons (PAHs) from Aircraft Exhaust

We used real-time monitors and low-volume air samplers to measure the potential human exposure to airborne polycyclic aromatic hydrocarbon (PAH) concentrations during various flight-related and ground-support activities of C-130H aircraft at an Air National Guard base. We used three types of photoelectric aerosol sensors (PASs) to measure real-time concentrations of particle-bound PAHs in a break room, downwind from a C-130H aircraft during a four-engine run-up test, in a maintenance hangar, in a C-130H aircraft cargo bay during cargo-drop training, downwind from aerospace ground equipment (AGE), and in a C-130H aircraft cargo bay during engine running on/off (ERO) loading and backup exercises. Two low-volume air samplers were collocated with the real-time monitors for all monitoring events except those in the break room and during in-flight activities. Total PAH concentrations in the integrated-air samples followed a general trend: downwind from two AGE units > ERO-loading exercise > four-engine run-up test > maintenance hangar during taxi and takeoff > background measurements in maintenance hangar. Each PAH profile was dominated by naphthalene, the alkyl-substituted naphthalenes, and other PAHs expected to be in the vapor phase. We also found particle-bound PAHs, such as fluoranthene, pyrene, and benzo[a]pyrene in some of the sample extracts. During flight-related exercises, total PAH concentrations in the integrated-air samples were 10-25 times higher than those commonly found in ambient air. Real-time monitor mean responses generally followed the integrated-air sample trends. These monitors provided a semiquantitative temporal profile of ambient PAH concentrations and showed that PAH concentrations can fluctuate rapidly from a baseline level < 20 to > 4,000 ng/m(3) during flight-related activities. Small handheld models of the PAS monitors exhibited potential for assessing incidental personal exposure to particle-bound PAHs in engine exhaust and for serving as a real-time dosimeter to indicate when respiratory protection is advisable.

Real-time and integrated measurement of potential human exposure to particle-bound polycyclic aromatic hydrocarbons (PAHs) from aircraft exhaust.

We used real-time monitors and low-volume air samplers to measure the potential human exposure to airborne polycyclic aromatic hydrocarbon (PAH) concentrations during various flight-related and ground-support activities of C-130H aircraft at an Air National Guard base. We used three types of photoelectric aerosol sensors (PASs) to measure real-time concentrations of particle-bound PAHs in a break room, downwind from a C-130H aircraft during a four-engine run-up test, in a maintenance hangar, in a C-130H aircraft cargo bay during cargo-drop training, downwind from aerospace ground equipment (AGE), and in a C-130H aircraft cargo bay during engine running on/off (ERO) loading and backup exercises. Two low-volume air samplers were collocated with the real-time monitors for all monitoring events except those in the break room and during in-flight activities. Total PAH concentrations in the integrated-air samples followed a general trend: downwind from two AGE units > ERO-loading exercise > four-engine run-up test > maintenance hangar during taxi and takeoff > background measurements in maintenance hangar. Each PAH profile was dominated by naphthalene, the alkyl-substituted naphthalenes, and other PAHs expected to be in the vapor phase. We also found particle-bound PAHs, such as fluoranthene, pyrene, and benzo[a]pyrene in some of the sample extracts. During flight-related exercises, total PAH concentrations in the integrated-air samples were 10-25 times higher than those commonly found in ambient air. Real-time monitor mean responses generally followed the integrated-air sample trends. These monitors provided a semiquantitative temporal profile of ambient PAH concentrations and showed that PAH concentrations can fluctuate rapidly from a baseline level < 20 to > 4,000 ng/m(3) during flight-related activities. Small handheld models of the PAS monitors exhibited potential for assessing incidental personal exposure to particle-bound PAHs in engine exhaust and for serving as a real-time dosimeter to indicate when respiratory protection is advisable.

Impact of task experience and individual factors on training-emphasis ratings.

This study included 2 sets of analyses examining the impact of task experience and individual factors on task ratings of training emphasis. Aerospace ground equipment mechanics in the U.S. Air Force completed surveys 8 months and 12 months after formal training. Mechanics rated how much formal training they would recommend for a sample of tasks. In the cross-sectional analyses, with tenure constant at 12 months, an individual's breadth of experience (number of tasks performed) and level of self-efficacy were found to have significant effects on training-emphasis ratings. The change analyses examined factors influencing changes in ratings of training emphasis from 8 to 12 months on the job

AN EVALUATION OF THE FEASIBILITY OF CONFIDENCE TESTING AS A DIAGNOSTIC AID IN TECHNICAL TRAINING

ABSTRACTThis report describes a study to determine the feasibility and the cost‐effectiveness of using confidence testing as a diagnostic aid in technical training programs. Two types of confidence testing, Pick‐One and Distribute 100 Points, were developed for comparison to conventional multiple‐choice testing. The study was carried out in two technical training courses, Aerospace Ground Equipment Repairman (AGE) and Jet Engine Mechanic (JEM), currently being taught at Chanute Air Force Base, Illinois. The criteria for feasibility included end of block examination grades, number of student remediational sessions, and both student and instructor attitudes. In addition, the relationship of various personality variables to confidence test scores was examined for both types of confidence testing. The major finding was that while scoring was somewhat more time consuming, end of block examination grades improved slightly and the number of remediations required declined slightly when either confidence testing method was employed. Other areas of investigation produced essentially null results.

A large-scale liquid fluorine flow facility development program.

A large-scale (500-gal) liquid fluorine flow facility in the Mojave Desert, California has been in operation for over two years. Constructed from off-the-shelf facility hardware, it is capable of instantaneous flow rates up to 250 Ib/sec for simulation of aerospace ground equipment and missile flight conditions. Unique facility features are 1) largest known capacity single-propellant flow loop for component and subsystem testing, 2) flange and fitting connections throughout, 3) dual-wall storage and receiver tanks, and 4) gaseous nitrogen blanket, maintained during other than leak checking and flow operations. Control consoles are used for remotely controlled flow operations. Pressure and temperature instruments (ambient to — 320°F) are used to monitor and provide test data. A systematic component evaluation program has been carried on. Testing has included valves, seals, quick disconnects, pressurization subsystems, and small combustors.

Aerospace ground equipment reduction by built- in testing.

Aerospace ground equipment reduction by built- in testing.

Design Approaches to Enhance Electromagnetic Compatibility of Aerospace Ground Support Systems

A generalized approach to the electromagnetic compatibility problem in electrical aerospace ground equipment (EAGE) systems is presented first by a control plan approach. This is augmented by the formulation of a grounding plan as the basis of good EAGE design. Criteria for packaging, shielding, and other control techniques is offered with emphasis on those elements which have the greatest effect on the final design.

Computer-Controlled Aerospace Ground Equipment for the AOSO Communications and Data-Handling Subsystem

Texas Instruments is presently engaged in design and development of the communication and data-handling subsystem (CDHS) and the associated aerospace ground equipment (AGE) for the Advanced Orbiting Solar Observatory (AOSO). This paper describes the AGE which will be used to test, monitor, exercise, and troubleshoot the CDHS. The observatory-class satellites are very complex and have sophisticated communications and data-handling equipment. The increase in complexity of satellite equipment has resulted in increased demands on the test capability of the checkout equipment. A computer-controlled checkout system has been selected as a result of an analysis of the satellite test requirements. By utilizing a general-purpose computer which controls special equipment designed for the AOSO, the requirement for a rapid, versatile checkout system has been met. This system is described in the following paragraphs.

Electromagnetic Interference Control Within Aerospace Ground Equipment for the Mcdonnell Phantom II Aircraft

This paper describes the program conducted by McDonnell Aircraft Corporation to assure Electromagnetic Compatibility (EMC) within Aerospace Ground Equipment (AGE) for tile Phantom II Aircraft. The wide variety of sophisticated AGE utilized presents many unique EMC problems. AGE/Aircraft compatibility considerations at McDonnell are of prime concern. Consistent grounding philosophies within AGE and compatible with airborne equipment has been established. Grounding systems are classified as primary power, secondary AC power, DC power, signal and radio frequency. Each equipment ground is classified and controlled accordingly. A Weapon System concept that results in the extensive use of shielded cabling is an important part of the McDonnell Aircraft EMI control approach. Design and testing of shielded cables, connectors, and connector back-shells has been accomplished. New designs to reduce radiation from various front panel mounted switches, jacks, meters, and lights have been developed. These include the grounding of "Bat" handles and shafts of switches and using waveguide below cut-off devices for jacks. Testing complex AGE to determine compliance with Military Specifications can become very time consuming. Methods and procedures to reduce test time, yet maintain a valid test, have been formulated.

Fuel Cell Battery - Aerospace Ground Equipment

Fuel Cell Battery - Aerospace Ground Equipment

General Criteria of Aerospace Ground Equipment

This paper describes the criteria by which the quality of Aerospace Ground Equipment is judged. It outlines the origin of the basic requirements for which AGE is designed and the conditions in which it must operate. The paper gives some examples of typical conditions. The need for conformance to the logistic conditions and operational methods of the launch vehicle customer is described. The unusually high demand on reliability is outlined by an example. The influence of hypergolic propellants on the design of AGE is shown. The sources of the AGE and the various steps in which AGE is tested--as well as the typical functions--are described.

Systems Engineering of Agena Aerospace Ground Equipment

This paper discusses problems of performing systems engineering in order to establish optimum and economical A. G. E. configurations in support of R & D missions in a multi-program, multicomplex environment. The combination of short lead-times, high launch rates and varied dynamic requirements of a large number of different yet simultaneous R & D operations provides a unique support situation. The problem has grown from support of the first successful orbiting vehicle in 1959 to last year's support of 36 successful launchings. The advantages of utilizing MIL-D-9412D to enhance systematic documentation of the A. G. E. system considerations and configuration will also be emphasized.

Aerospace Ground Equipment for Doppler Navigation Systems

This paper presents a philosophy of system maintenance and the principles upon which it is based. Levels of maintenance and the different test program needs at these different levels are discussed. A case history of older Doppler System test equipments is presented, showing how and why the equipment evolved to its present state. A more detailed example is presented of a current support equipment program.

Mating Ground Electrical Power to Aerospace Ground Equipment and the Flight Vehicle

Present day aerospace ground electronic equipment and the flight vehicle electronic equipment cannot tolerate the quality of electrical power allowed by existing specifications. The increasing use of digital computers and logic type switching devices requires that the regulated rectified power used by these devices be free from transients. The voltage transient problem from the electronic designers' viewpoint is analyzed. A program is proposed to reduce transients to acceptable limits and revise the specifications to include these limits.