Shop and Personal Safety

1-1 Safety, Ground Operations, & Servicing Chapter 1 Aviation maintenance technicians (AMTs) devote a portion of their aviation career to ground handling and operating aircraft. Technicians also need to be proficient in operating ground support equipment. The complexity of support equipment and the hazards involved in the ground handling of aircraft require that maintenance technicians possess a detailed knowledge of safety procedures used in aircraft servicing, taxiing, run-up, and in the use of ground support equipment. The information provided in this chapter is intended as a general guide for safely servicing and operating aircraft.

Introducing human factors to aircraft maintenance personnel makes them aware of how it affects maintenance performance. Although there are many human factors involved when dealing with maintenance performance, several areas can be considered. Some of these include fatigue, deadline pressure, stress, distractions, poor communication skills, complacency, and lack of information. Maintenance technicians need to understand how human factors can impact their performance and safety while completing maintenance tasks.

Shop Safety

Keeping the shop, hangars, and flight line clean is essential to safety and efficient maintenance. The highest standards of orderly work arrangements and cleanliness must be observed during the maintenance of aircraft. Where continuous work shifts are established, the outgoing shift removes and properly stores personal tools, rollaway boxes, work stands, maintenance stands, hoses, electrical cords, hoists, crates, and boxes that were needed for the work to be accomplished. Signs are posted to indicate dangerous equipment or hazardous conditions. Additionally, there are signs that provide the location of first aid and fire equipment. Safety lanes, pedestrian walkways, and fire lanes are painted around the perimeter inside the hangars. This is a safety measure to prevent accidents and to keep pedestrian traffic out of work areas.

Safety is everyone’s business. However, technicians and supervisors must watch for their own safety and for the safety of others working around them. Communication is key to ensuring everyone’s safety. If other personnel are conducting their actions in an unsafe manner, communicate with them, reminding them of their safety and that of others around them.

Electrical Safety

Physiological Safety

Working with electrical equipment poses certain physiological safety hazards. When electricity is applied to the human body, it can create severe burns in the area of entrance and at the point of exit from the body. In addition, the nervous system is affected and can be damaged or destroyed. To safely deal with electricity, the technician must have a working knowledge of the principles of electricity and a healthy respect for its capability to do both work and damage. Wearing or use of proper safety equipment can provide a psychological assurance and physically protect the user at the same time. The use of rubber gloves, safety glasses, rubber or grounded safety mats, and other safety equipment contributes to the overall safety of the technician working on or with electrical equipment.

Two factors that affect safety when dealing with electricity are fear and overconfidence. These two factors are major causes of accidents involving electricity. While a certain amount of respect for electrical equipment is healthy and a certain level of confidence is necessary, extremes of either can be deadly. Lack of respect is often due to lack of knowledge. Personnel who attempt to work with electrical equipment and have no knowledge of the principles of electricity lack the skills to deal with electrical equipment safely. Overconfidence leads to risk taking. The technician who does not respect the capabilities of electricity will, sooner or later, become a victim of electricity’s power.

Fire Safety

Anytime current flows, whether during generation or transmission, a by-product is heat. The greater the current flow, the greater the amount of heat created. When this heat becomes too great, protective coatings on wiring and other electrical devices can melt, causing shorting. That in turn leads to more current flow and greater heat. This heat can become so great that metals can melt, liquids vaporize, and flammable substances ignite. An important factor in preventing electrical fires is to keep the area around electrical work or electrical equipment 1-2 clean, uncluttered, and free of all unnecessary flammable substances. Ensure that all power cords, wires, and lines are free of kinks and bends that can damage the wire. Never place wires or cords where they may be walked on or run over by other equipment. When several wires inside a power cord are broken, the current passing through the remaining wires increases. This generates more heat than the insulation coatings on the wire are designed to withstand and can lead to a fire. Closely monitor the condition of electrical equipment. Repair or replace damaged equipment before further use.

Safety Around Compressed Gases Compressed air, like electricity, is an excellent tool when it is under control. A typical nitrogen bottle set is shown in Figure 1-1. The following “dos and don’ts” apply when working with or around compressed gases: • Inspect air hoses frequently for breaks and worn spots. Unsafe hoses must be replaced immediately. • Keep all connections in a “no-leak condition.” • Maintain in-line oilers, if installed, in operating condition. • Ensure the system has water sumps installed and drained at regular intervals. • Filter air used for paint spraying to remove oil and water.

• Never use compressed air to clean hands or clothing. Pressure can force debris into the flesh leading to infection. • Never spray compressed air in the area of other personnel. • Straighten, coil, and properly store air hoses when not in use. • Many accidents involving compressed gases occur during aircraft tire mounting. To prevent possible personal injury, use tire dollies and other appropriate devices to mount or remove heavy aircraft tires. When inflating tires on any type of aircraft wheels, always use tire cage guards. Extreme caution is required to avoid over inflation of high-pressure tires because of possible personal injury. Use pressure regulators on high-pressure air bottles to eliminate the possibility of over inflation of tires.

Tire cages are not required when adjusting pressure in tires installed on an aircraft. Safety Around Hazardous Materials Material safety diamonds are important with regard to shop safety. These diamond-shaped labels are a simple and quick way to determine the risk of hazardous material within the associated container and, if used properly with the tags, indicate what personal safety equipment to use. The most observable portion of the Safety Data Sheets (SDSs) (formerly known as Material Safety Data Sheet (MSDS)) label is the risk diamond. It is a four-color segmented diamond that represents flammability (red), reactivity (yellow), health (blue), and special hazard (white). In the flammability, reactivity, and health blocks, there is a number from 0 to 4. Zero represents little or no hazard to the user, while 4 means that the material is very hazardous. The special hazard segment contains a word or abbreviation to represent the specific hazard. Some examples are RAD for radiation, ALK for alkali materials, Acid for acidic materials, and CARC for carcinogenic materials. The letter W with a line through it stands for high reactivity to water. [Figure 1-2] The SDS is a more detailed version of the chemical safety issues. These forms have the detailed breakdown of the chemicals, including formulas and action to take if personnel come in contact with the chemicals. All sheets have the same information requirements; however, the exact location of the information on the sheet may vary depending on the SDS manufacturer. These forms are necessary for a safe shop that meets all the requirements of the governing safety body, the U.S. Department of Labor Occupational Safety and Health Administration (OSHA).

Safety Around Machine Tools Hazards in a shop increase when the operation of lathes, drill presses, grinders, and other types of machines are used. Each machine has its own set of safety practices. The following discussions are necessary to avoid injury. The drill press can be used to bore and ream holes, to do facing, milling, and other similar types of operations. The following precautions can reduce the chance of injury: • Wear eye protection. • Securely clamp all work. • Set the proper revolutions per minute (rpm) for the material used. • Do not allow the spindle to feed beyond its limit of travel while drilling.

• Stop the machine before adjusting work or attempting to remove jammed work. • Clean the area when finished. Lathes are used in turning work of a cylindrical nature. This work may be performed on the inside or outside of the cylinder. The work is secured in the chuck to provide the rotary motion, and the forming is done by contact with a 1-3 4 W 32 securely mounted tool. The following precautions can reduce the chance of injury: • Wear eye protection. • Use sharp cutting tools. • Allow the chuck to stop on its own. Do not attempt to stop the chuck by hand pressure. • Examine tools and work for cracks or defects before starting the work.

• Do not set tools on the lathe. Tools may be caught by the work and thrown. • Before measuring the work, allow it to stop in the lathe. Milling machines are used to shape or dress; cut gear teeth, slots, or key ways; and similar work. The following precautions can reduce the chance of injury: • Wear eye protection. • Clean the work bed prior to work. • Secure the work to the bed to prevent movement during milling. • Select the proper tools for the job. • Do not change the feed speed while working. • Lower the table before moving under or away from the work. • Ensure all clamps and bolts are passable under the arbor.

Grinders are used to sharpen tools, dress metal, and perform other operations involving the removal of small amounts of metal. The following precautions can reduce the chance of injury: • Wear eye protection, even if the grinder has a shield. • Inspect the grinding wheel for defects prior to use. • Do not force grinding wheels onto the spindle. They fit snugly but do not require force to install them. Placing side pressure on a wheel could cause it to explode. • Check the wheel flanges and compression washer. They should be one-third the diameter of the wheel. • Do not stand in the arc of the grinding wheel while operating in case the wheel explodes.

Welding must be performed only in designated areas. Any part that is to be welded must be removed from the aircraft, if possible. Repair would then be accomplished in a controlled environment, such as a welding shop. A welding shop must be equipped with proper tables, ventilation, tool storage, and fire prevention and extinguishing equipment. 1-4 Welding on an aircraft should be performed outside, if possible. If welding in the hangar is necessary, observe these precautions: • During welding operations, open fuel tanks and work on fuel systems are not permitted. • Painting is not permitted. • No aircraft are to be within 35 feet of the welding operation.

• No flammable material is permitted in the area around the welding operation. • Only qualified welders are permitted to do the work. • The welding area is to be roped off and placarded. • Fire extinguishing equipment of a minimum rating of 20B must be in the immediate area with 80B rated equipment as a backup. • Trained fire watches are to be present in the area around the welding operation. • The aircraft being welded must be in a towable condition, with a tug attached, and the aircraft parking brakes released. A qualified operator must be on the tug and mechanics available to assist in the towing operation should it become necessary to tow the aircraft. If the aircraft is in the hangar, the hangar doors are to be open.

Flight Line Safety Hearing Protection The flight line is a place of dangerous activity. Technicians who perform maintenance on the flight line must constantly be aware of what is going on around them. The noise on a flight line comes from many places. Aircraft are only one source of noise. There are auxiliary power units (APUs), fuel trucks, baggage handling equipment, and so forth. Each has its own frequency of sound. Combined all together, the noise on the ramp or flight line can cause hearing loss. There are many types of hearing protection available. Hearing protection can be external or internal. Earmuffs or headphones are considered external protection. The internal type of hearing protection fits into the auditory canal. Both types reduce the sound level reaching the eardrum and reduce the chances of hearing loss.

Hearing protection is essential when working with pneumatic drills, rivet guns, or other loud tools. Even short duration exposure to these sounds can cause hearing loss because of their high frequency. Continued exposure will cause hearing loss. Foreign Object Damage (FOD) Foreign object damage (FOD) is any damage to aircraft, personnel, or equipment caused by any loose object. These loose objects can be anything, such as broken runway concrete, shop towels, safety wire, etc. To control FOD, keep ramp and operation areas clean, have a tool control program, and provide convenient receptacles for used hardware, shop towels, and other consumables.

Never leave tools or other items around the intake of a turbine engine. The modern gas turbine engine creates a low-pressure area in front of the engine that causes any loose object to be drawn into the engine. The exhaust of these engines can propel loose objects great distances with enough force to damage anything that is hit. The importance of a FOD program cannot be overstressed when a technician considers the cost of engines, components, or a human life. Safety Around Airplanes As with the previously mentioned items, it is important to be aware of propellers. Technicians cannot assume the pilot of a taxiing aircraft can see them and must stay within the pilot’s view while on the ramp area. Turbine engine intakes and exhaust can also be very hazardous areas. Smoking or open flames are not permitted anywhere near an aircraft in operation. Be aware of aircraft fluids that can be detrimental to skin. When operating support equipment around aircraft, be sure to allow space between it and the aircraft, and secure it so it cannot roll into the aircraft. All items in the area of operating aircraft must be stowed properly.

Safety Around Helicopters Every type of helicopter has different features. These differences must be learned to avoid damaging the helicopter or injuring the technician. When approaching a helicopter while the blades are turning, adhere to the following guidelines to ensure safety. • Observe the rotor head and blades to see if they are level. This allows maximum clearance when approaching the helicopter. • Approach the helicopter in view of the pilot. • Never approach a helicopter carrying anything with a vertical height that the blades could hit. This could cause blade damage and injury to the individual.

• Never approach a single-rotor helicopter from the rear. The tail rotor is invisible when operating. • Never go from one side of the helicopter to the other by going around the tail. Always go around the nose of the helicopter. When securing the rotor on helicopters with elastomeric 1-5 bearings, check the maintenance manual for the proper method. Using the wrong method could damage the bearing.

Fire Safety

Performing maintenance on aircraft and their components requires the use of electrical tools that can produce sparks, heat-producing tools and equipment, flammable and explosive liquids, and gases. As a result, a high potential exists for fire to occur. Measures must be taken to prevent a fire from occurring and to have a plan for extinguishing it. The key to fire safety is knowledge of what causes a fire, how to prevent it, and how to put it out. This knowledge must be instilled in each technician, emphasized by their supervisors through sound safety programs, and occasionally practiced. Airport or other local fire departments can normally be called upon to assist in training personnel and helping to establish fire safety programs for the hangar, shops, and flight line.

Fire Protection

Requirements for Fire to Occur Three things are required for a fire. Remove any one of these things and the fire extinguishes: 1. Fuel—combines with oxygen in the presence of heat, releasing more heat. As a result, it reduces itself to other chemical compounds. 2. Heat—accelerates the combining of oxygen with fuel, in turn releasing more heat. 3. Oxygen—the element that combines chemically with another substance through the process of oxidation. Rapid oxidation, accompanied by a noticeable release of heat and light, is called combustion or burning. [Figure 1-3] Classification of Fires For commercial purposes, the National Fire Protection Association (NFPA) has classified fires into three basic types: Class A, Class B, and Class C.

1. Class A fires involve ordinary combustible materials, such as wood, cloth, paper, upholstery materials, and so forth. 2. Class B fires involve flammable petroleum products or other flammable or combustible liquids, greases, solvents, paints, and so forth. 3. Class C fires involve energized electrical wiring and equipment. A fourth class of fire, the Class D fire, involves flammable metal. Class D fires are not commercially considered by the NFPA to be a basic type of fire since they are caused by a Class A, B, or C fire. Usually Class D fires involve magnesium in the shop, or in aircraft wheels and brakes, or are the result of improper welding operations.

Any one of these fires can occur during maintenance on or around, or operations involving aircraft. There is a particular type of extinguisher that is most effective for each type of fire. Types and Operation of Shop and Flight Line Fire Extinguishers Water extinguishers are the best type to use on Class A fires. Water has two effects on fire. It deprives fire of oxygen and cools the material being burned. Since most petroleum products float on water, water-type fire extinguishers are not recommended for Class B fires. Extreme caution must be used when fighting electrical fires (Class C) with water-type extinguishers. All electrical power must be removed or shut off to the burning area. Additionally, residual electricity in capacitors, coils, and so forth must be considered to prevent severe injury or possibly death from electrical shock.

Never use water-type fire extinguishers on Class D fires. The cooling effect of water causes an explosive expansion of the metal, because metals burn at extremely high temperatures. Water fire extinguishers are operated in a variety of ways. Some are hand pumped, while others are pressurized. The pressurized types of extinguishers may have a gas charge stored in the container with the water, or it may contain a “soda-acid” container where acid is spilled into a container of soda inside the extinguisher. The chemical reaction of the soda and the acid causes pressure to build inside the fire extinguisher, forcing the water out.

Carbon dioxide (CO2) extinguishers are used for Class A, B, and C fires, extinguishing the fire by depriving it of oxygen. [Figure 1-4] Additionally, like water-type extinguishers, CO2 cools the burning material. Never use CO2 on Class D fires. As with water extinguishers, the cooling effect of CO 2 on the hot metal can cause explosive expansion of the metal. When using CO 2 fire extinguishers, all parts of the extinguisher can become extremely cold, and remain so for a short time after operation. Wear protective equipment or take other precautions to prevent cold injury, such as frostbite. Extreme caution must be used when operating CO2 fire extinguishers in closed or confined areas. Not only can the fire be deprived of oxygen, but so too can the operator.

CO2 fire extinguishers generally use the self-expelling method of operation. This means that the CO2 has sufficient pressure at normal operating pressure to expel itself. This