"Gee Whiz" Technology
Part II
By Fred Workley
October 1998
Because I write articles for aircraft maintenance personnel, I read a lot. I continually come across new ideas and applications that we may eventually see on the hangar floor.
An excerpt from CHI Companion 95, in an article by Jane Siegel, written for Technician (Spring 1996), caught my attention.
This article discussed the study of human-computer (HCI) or computer-human interactions (CHI); as well as "hypertext," which is the display of information in a computer format instead of as a conventional, plain text, standard-English document.
The study looked at aircraft maintenance workers wearing visual interfaces and collaborative systems to support troubleshooting and repair work. The results showed that there were improvements in coordination and ease of work when maintenance personnel used the hypertext, video, and audio capability. Wearable computers and telecommunications allow maintenance personnel at remote sites to access information and contact everyone who can help them get the aircraft flying again.
An aircraft maintenance technician may clip a very small (1.5 pound), wearable computer system on a belt. This computer will have rapid response, speech input (with possible speech recognition), wireless audio, and a head-mounted visual display with fine resolution for hands-free operation. All components are miniaturized and supported by a radio network. The technician will have immediate access to current procedures from the maintenance manual and the latest parts information with aircraft effectivity.
Along with better coordination and gaining faster access to information, these new technologies may also:
(1) Spread organizational expertise among the technicians
(2) Provide fast access to procedural, process, and schematic information for problem solving from local and off-site sources
(3) Support process re-engineering
(4) Improve organizational memory
The goal of the system is to improve task performance. Most important, I see these systems as a way to reduce potential human errors. The research on the human-system interaction focuses on task performance, displays that are easy-to-read, and hands-free operation. Other factors involve ease of sharing information and adapting this technology to a particular organization with its unique corporate culture.
In evaluating these systems in an organization, some of your considerations are:
(1) Can your people adapt from using paper manuals to on-line, hypertext computer manuals in a paperless environment?
(2) Are maintenance tasks performed equally efficient solo or with a collaborative, remote helper?
(3) Does the presence of a video link providing a real time image and two way communications capability between the field technician and the helper/expert/product representative by permitting the helper to see what the technician sees save time and increase accuracy?
One of the concerns regarding these systems are the individual maintenance technician's adaptation to the system due to differences with the individual's eyes. It takes some getting used to seeing this type of on-line application. Initially, it is more difficult to read the applicable text and see the diagrams on these systems than on paper. Sometimes, technicians link to the hypertext, which gives more details than they need to define the existing problem with the aircraft, before they get an overall perspective. You need some idea of the problem from troubleshooting that leads you toward the specific task or procedure needed to fix the problem.
However, with more familiarity using this wearable computer system, the aircraft technician's time to complete the task and accuracy may be improved. Army engineers are using commercial off-the-shelf telemaintenance systems to repair communications equipment in the field. This telemaintenance system is made up of a small video camera and a modem with external probes for testing electronics. The user can configure the system to use telephone lines, dedicated data lines, or satellite links.
After field technicians establish the link with a service center, they send video of the faulty equipment and identify the installed circuit cards. The specialists at the service center use schematics to tell the field technicians how to troubleshoot the card. Also, the field technicians use probes, such as voltage meters, to send data that tells the service center technicians where to make adjustments to restore the system to the correct specifications. These systems are available for real-time repair of aircraft systems, avionics, and electronics. The objective is to "reduce the number of emergency repair teams deployed to field locations" and "have a means to make repairs in hours instead of days."
We need intelligent, ultra-low power displays backed by software programs that show the technicians how the systems under review really operate. Some of the new miniature flat panels or micro-displays use liquid crystal displays, with some controlled by the use of plasma gas cells instead of silicon transistors. There continue to be rapid improvements in direct-view displays for commercially available,"ruggedized" laptops that are lightweight, thin, and have low power consumption. The systems need to support either all-digital controls or remote analog controls, and they must store as many as sixteen display formats.
The real advances in the last three years have been in the use of active-matrix liquid crystal display (AMLCD) technology for helmet-mounted displays. These miniature flat panels are smaller than an inch on diagonal. These can be used to display schematics and other computer based data. The next step is to build the display into your safety glasses with the micro-display image source in the glass frame and the optical emitter embedded in the lenses. Eventually, low powered red, green, and blue lasers will send a pattern through the maintenance technician's eye pupil with the image focused on the retina. The effect is like viewing high-quality video at arm's length.
By now you are saying, "NOT ME." There's more. There is already 3D (three-dimensional) software available that can help you visualize the part and all its connections before you remove it. Real-time systems are being designed with reflective memory. This works by duplicating (reflecting) the computer data from the memory board of one computer to the memory board of a parallel memory board in another system. A synchronization primitive ensures that the two boards remain in sync. This is communicated over some type of interconnect. It is possible that this interconnect could be fiber optics. Fly by light you say? Aircraft maintenance technicians are going to have to maintain on-aircraft systems receiving ground based telemetry that will be fed to the aircraft controls in a real-time environment.
Let me give you some examples that you may soon see on the hangar floor.
One is a smart tire. The tires will have MicroElectroMechanical Systems (MEMS) with embedded sensors and actuators that will interface directly with microprocessor-based information processing systems that are designed to improve maintenance and cut costs. The MEMS monitor pressure, temperature, and tire wear. They provide a unique code to identify the information from that specific tire. The idea is that knowing this information will permit technicians to improve their routine maintenance procedures. The same technology can install a small transponder in the tire which when interrogated, can provide the same information along with identification. The software for this system was developed for the remote long distance barcode reading systems.
Other uses for computers in maintenance are for processing information from infrared temperature sensors for example. There are new aircraft applications that require precision optics and sensing of high temperatures of 0 to 570 degrees F. The powered electronics must be very noise resistant over long distances so that data is not distorted.
How about processing information from electronic accelerometers used for navigation when the aircraft is out of range of the Global Positioning System (GPS)? This replaces heavy electromechanical systems employing cantilever beam and pendulum inertial systems. The variable capacitance accelerometer is on an array of three, micromachined single-crystal silicon 2-inch wafers. The whole sensor can weigh between 3.6 to 7 grams. They can stand shock loads up to 10,000Gs and can measure as little as +/- 2 G, or up to 100 G. The temperature range is 165 to 250 degrees F.
The next two examples use predictive maintenance techniques. The first is checking the tightness of bolts and fasteners without ever removing them. This is done by ultrasonic sensors either applied to the bolt with a liquid coupling, or built-on sensors with wire to remote locations on the aircraft. The computer must interpret this information and store it for future comparisons to determine if the torque on that particular fastener has increased or decreased over time. The same kind of data, but continuous real-time information will have to be received from oxygen sensors that monitor the oxygen level in the ullage (air/hydrocarbon fuel vapors over the fuel) of the aircraft fuel tanks. An inerting gas, either carbon dioxide from a frozen liquid source or nitrogen is then metered into the tank to keep the fuel/air mixture and oxygen content below that which could support combustion. Aircraft maintenance technicians will have to correct the system data bus faults indicating the need for maintenance as identified by the data available to them through their computer interface.
But, you say that you only work on engines. Computers also will be a necessity for you to maintain engines. Get ready for the next generation of FADECs (full-authority digital engine controls), to monitor and manage engine performance. The next advance is the high-performance engine-control systems that are fully integrated into a single flight and propulsion system. It will be impossible to tell where the engine stops and the airframe begins. Electronic engine controls (EECs) are the present heart of the FADECs. However, they are serial digital links. Through fuzzy logic and neutral networks (no complete on or off), the central EEC can be eliminated and the result will be a fuel control viewed as a continuum. This will affect you because neutral systems require a new way of thinking. They will, with the aid of computers, improve the efficiency of troubleshooting based on diagnostic models of the fuel control system. Again, these systems will permit predictive maintenance.
Computers will play an ever-increasing role in aircraft maintenance. Another example is Micropower Impulse Radar — a technology that is available right now — all it needs is someone to make it commercially available. Micropower Impulse Radar (MIR) is pulsed radar with an ultra-wide band, but it emits short pulses. It is compact and built out of common electronic components with a cost of less than twenty dollars. This radar is based on the world's highest power laser system — the Lawrence Livermore National Laboratory (LLNL) 100-trillion-watt Nova laser. The pulsed laser generates high-speed sub-nanosecond events that can be recorded. The radar has a special fast electronic circuitry for driving a 33 gigasample-per-second transit digitizer that records events. This new circuit makes this new small, low-power radar system possible. The first application will be a liquid fluid level sensing device (electronic dipsticks). The second application for aircraft will be through-wall imaging. The MIR pulse generation circuitry is ideal for radar systems. Each pulse is less than a billionth of a second, and each MIR emits about two million of these pulses per second. Actual pulse repetition rates are coded with random noise to reduce the possibility of interference from other radars. This means that each pulse is tuned to itself. The same pulse is used for transmitting that is used to receive the signal. The received signal can be sampled. With pulses so short, the MIR operates across a wider band of frequencies, thus giving it high-resolution accuracy. This results in less interference from other radars.
The MIR can operate for years on one AA battery. The reason for this is that current is only drawing extremely low power during the short and infrequent pulse time. Another advantage is that the microwaves emitted by the pulse are at extremely low microwatt level. The system is not triggered by background clutter. This radar is medically safe since the MIR emits less than one-millionth the energy of a cellular telephone. The antenna configuration for standard motion sensor will be only 1.5 inches.
Whether you respond to all this new technology with "Gee Whiz!" or, "No Way!" You will have to learn new ways and new lessons while using computers to "keep-em-flying."
