April 1, 2001


In the maintenance business, the hazards are not in the day-to-day flight operations, but in the routine of performing our jobs

By Jim Sparks

April 2001

A form of the statement "Aviation in itself is not inherently dangerous, it is, however, very unforgiving" is found hanging on the walls of many flight departments accompanying a picture of an early aircraft hanging precariously from tree limbs. Most of us realize the fears tied to our industry and in many ways, due to the efforts of the aircraft maintenance community, aviation is, without doubt, the safest way to travel. For those of us in the maintenance business, the hazards are not in the day-to-day flight operations but in the routine of performing our jobs. The technical support of aircraft involves exposure to harmful chemicals, potentially lethal electrical shocks, and rapidly moving components. Hazards can even arise from extending aid to a fellow worker who may be injured. Working as an electrician, I have had the opportunity to see the effects of electrical shock as well as the disfiguration that accompanies the welding of a wedding ring to an electrical contactor. I have also learned first-hand the benefit of a properly installed high-tension ignition lead tester.

Definition of "hazard"
A hazard is defined as "danger of loss" or "peril" and manifest themselves in many forms including sharp items that could inflict stab wounds or cuts; heavy objects that could roll over; devices that could fall; heat; cold; light; radiation; flying objects; shocks; and frequent exposure to chemicals or dangerous materials including harmful dust or vapors; and of course, motion hazards are always present. Situational awareness is the one factor that will greatly reduce workplace injuries.

Career-altering events
Something as simple as replacing a starter generator on an engine or Auxiliary Power Unit (APU) could turn out to be a career-altering event. Some think, "How could something so day-to-day be considered a potential hazard?" First of all, there is the possibility for electrical shock if adequate precautions are not made to disable the aircraft electrical power system. There is, of course, the starter generator itself — many weigh around 80 lbs. and if not properly lifted, could result in back strain or even a hernia. Once this dead weight is lifted, the potential for dropping it exists. Not only will this put the lower extremities of the installer at risk, but anyone assisting in the replacement is also in harm’s way. This operation may also expose those involved to engine oil, another would-be hazard.

Accident factors
For any accident to occur, two factors need to be present: a potential hazard and a potential victim. Being constantly vigilant of our surroundings will have a significant impact in reducing the likelihood of becoming a victim. Proper preparation for any assignment or task should involve consideration of what could go wrong. One documented case exists where an avionics technician was assigned the job of replacing the flightdeck microphone plugged into the co-pilots control column. What could possibly go wrong? On the way to the cockpit, the technician walked past the external hydraulic power unit connected to the aircraft. Once the technician was seated in the co-pilots seat and had tracked it fully aft to facilitate bending over to gain access to the plug, the unexpected happened. The other technicians who had just received their assignments after shift change, activated the hydraulic power unit causing the flight control column to move aft; pinning the technician in such a way that he could not apply a forward force to free himself. Although no permanent injuries resulted, the avionics technician was off work for several days with back spasms.
Why did this happen? In this case, it is evident that the avionics technician expected someone to verify an "All Clear" before hydraulics were applied and the technician applying the external hydraulic power had no idea that someone was working in the aircraft. Could this situation have been avoided?
Even the simplest task in aircraft maintenance will involve some element of risk. These risks can be significantly reduced with a bit of consideration before performing the job. Safeguards are the key and are available in the form of Personal Protective Equipment (PPE).

Personal protective equipment
Selection of appropriate equipment is based on professional expertise and common sense. Even the U.S. government’s Occupational Safety and Health Administration (OSHA) has produced guidelines for the selection of PPE and are found in Title 29, Code of Federal Regulations (CFR) 1910, Subpart I Appendix B of the OSHA Standards.
The first step in determining suitable PPE is to survey the area and determine the possible hazards. Some examples include:
• Mechanical impacts
• Penetration by sharp objects
• Roll over by heavy objects
• Chemicals
• Harmful Dust
• Heat
• Vapors
• Electrical hazards
• Motion hazards
• Biological contaminants
Once the different types of risk are assessed, the level of risk should then be considered. What’s the likelihood for something to go wrong?

Multiple risks
Exposure to toxic substances are all but unavoidable in this business and in many cases, those being exposed are unaware of the potential danger. Frequently in aircraft maintenance, exposure to several hazards simultaneously are likely. For example, during a complete avionics refurbishment on an older aircraft, the technicians were required to remove plumbing used to deliver hot engine bleed-air to the air-conditioning systems as well as noise-deadening mats throughout the cabin. These air-pipes were wrapped in an insulating blanket made of asbestos and the noise suppression devices fabricated from lead. It should be of utmost importance to know the materials you’re working with.
Popular cleaning solvents such as Methylethylketone (MEK) can be unhealthy if appropriate protections are not observed.
Adhesives can also pose a significant risk and the Material Safety Data Sheet (MSDS) 3M 1300L recommends to "avoid prolonged breathing of vapors" and to select a half-mask organic vapor respirator will working with and around this substance. Even working in a confined space in the presence of a hydraulic mist can cause serious health problems. Mineral-based hydraulic fluids can cause vomiting accompanied by pneumonitis.

Breathe easier with proper respirators
Respirator selection is best made by first determining the type of exposure. Items to be considered are the type of contaminant. Is it dust, fumes, mist, gas or a vapor? If it is a chemical, is an MSDS available? Other factors that will help determine the type of respirator used include:
• Type and amount of hazardous exposure
• Knowledge of respirators and their relevant characteristics
• Job Site
• Personal medical characteristics
Job site is one factor in aircraft maintenance that many of us have no control over. Many large commercial aircraft have immense, well-ventilated avionics compartments as well as access doors that allow ample admission to the area forward of the main instrument panel. For those of us in general aviation, the job site could be anywhere from a heated and/or air-conditioned hangar to a remote location in some far off corner of the world. In most cases, those of us involved in avionics maintenance will at some point in our career find ourselves in some tightly constrained area where it may be possible to see your target with one eye, while still getting two fingers in to accomplish the task at hand. Situations such as this may have an impact on respirator or other PPE selection. Personal medical conditions are another major consideration when selecting a breathing apparatus.
There are three categories of Respirator and they include: Air Purifying, Supplied Air, and Self-Contained Breathing Apparatus (SCBA).
Air-Purifying Respirator – contains filters or canisters that remove contaminants by passing the ambient air through the air-purifying element before it reaches the user. These devices can capture dust, mist, and fumes but provide no protection against gases or vapors. Those involved in health care have a special Air-Purifying Particulate Respirator that will reduce the wearer’s exposure to blood and body fluids.
Atmosphere-Supplying Respirators – deliver clean air to the user from a source other than the air surrounding the wearer. An Air-Purifying Combination Respirator will provide protection against ingress of particulates as well as gas and vapors, whereas an Air-Purifying Gas/Vapor Respirator does not protect against airborne particulate, but does use chemical filters to remove gas and vapors. Air-Supplied Respirators use a hose and an external and remote compressed air source and are effective against most contaminants, but the drawbacks include bulk and possible restriction to movement in confined space. Combined Air-Supplying and Self-Contained units that have a backup air tank in the event the primary external air source fails, but this type may limit mobility.
Self-Contained Breathing Apparatus (SCBA) uses a fully mobile Clean-Air Supply Pack that is worn by the user. While it increases mobility, maneuverability in tight areas may be reduced.
In addition to proper equipment selection, an equally important factor is proper fit. After all, if a breathing apparatus fails to prevent contamination, it is not providing the user with the level of protection that was intended. Facial hair such as a beard may restrict the user from all but a full-hooded, Air-Supplied type device. Of course, those exposed to electrical devices will want to ensure that their PPE will not subject the wearer to any additional danger.

First-aid hazards
Another peril almost everyone dreads is encountering a friend or co-worker who has been involved in an accident. Unfortunately in this day and age, all blood or other bodily fluids should be considered infectious regardless of the perceived status of the source. It is essential to ensure that the injured person receives necessary help as quickly as possible; however, protection for the caregiver against disease transmission is also an important consideration.
The Occupational Safety and Health Administration (OSHA) mandates that most corporations implement an Exposure Control Plan to minimize employee exposure to body fluids. Often, these plans include an immunization program for those persons at risk. Occupational exposure in the aircraft maintenance industry comes in the form of hangar accident, rendering first aid and CPR, plus accident investigation or aircraft recovery.

How disease spreads
The disease process begins when a disease-causing agent called a pathogen enters the human body. Both bacteria and virus are considered pathogens and have distinctly different properties. Bacteria does not depend on a host for life and in many cases can be controlled by antibiotics. Some examples of bacteria are meningitis, scarlet fever and tetanus. A virus, on the other hand, does depend on a host and antibiotics are generally ineffective. The best control over viruses is a healthy immune system. Some examples of viruses are the common cold, hepatitis, and HIV. For disease spread to occur, four elements need to be in place:
1. Presence of a pathogen
2. Adequate amount of pathogen
3. Personal susceptibility
4. Entry site
The one element that we often have control over is the "Entry site," and there are four methods of pathogen access to the body.
Direct contact – touching possible contaminated bodily fluids.
Indirect contact – touching objects that have touched contaminated body fluids.
Airborne disease transmission – inhaling droplets from a cough or sneeze.
Vector-borne transmission – occurs through insect bites. In the event of clean-up after an accident, it is important to note that a virus such as Hepatitis can remain alive even in dry blood for up to two days.
Decontamination of an accident site should be accomplished using chlorine bleach or alcohol with all cleaning materials being properly disposed of in containers identified with a BIOHAZARD label permanently attached. Disease prevention can be accomplished on the job by the effective use of Personal Protective Equipment (PPE) and Personal Hygiene Practices. PPE is adequate when it does not permit blood or other infectious material to pass through to clothing, skin, eyes, mouth and any mucous membrane. Personal hygiene includes thorough washing using soap and water for at least 15 minutes.

Exposure evaluation
Most company exposure control plans include a post exposure evaluation and a follow-up. Different states have different laws concerning individual right to privacy and may affect the testing of an individual’s blood for the presence of pathogens. It is up to each of us to know what our employers offer regarding our protection. Investigation of the OSHA web site www.osha.gov can provide answers to many questions regarding minimum standards. Also, the American Red Cross offers a short course titled Preventing Disease Transmission.
After all, it’s not aviation that’s hazardous, but rather the environments in which aircraft and its maintainers exist that can be problematic. Awareness of potential hazards, use of personal protective equipment, hazard training, along with common sense can ensure most of us a long and healthy career.