pulled against the screen, and small items can be pulled
through the screen. This results in thousands of dollars
of damage to the engine.
Exhaust Area Hazards
Jet engine exhaust also creates hazards. Tests
show that while the carbon monoxide content of jet
exhaust is low, other gases are present that irritate the
eyes. Less noticeable, but as important, is the
respiratory irritation that may be caused by exhaust
The two major hazards of jet engine exhaust are
the high temperature and high velocity of the exhaust
gases from the tailpipe. High temperatures are found
up to several hundred feet from the tailpipe, depending
on wind conditions. Closer to the aircraft,
temperatures are high enough to damage asphalt
pavement. The blast from the exhaust is strong enough
to knock a person down at close distances and can even
blow a body off of the flight deck overboard. Do not
take the signs lightly. BEWARE OF JET BLAST.
When a jet engine is started, excess fuel
accumulates in the tailpipe. When the fuel ignites, long
flames can be blown out of the tailpipe. All flight line
personnel should be aware of this hazard, and all
flammable materials should be kept clear of the danger
During maximum power settings, the high
velocity of the exhaust gases may pick up and blow
loose dirt, sizable rocks, sand, and debris several
hundred feet. This is an eye and FOD hazard.
Therefore, you should use caution when parking an
aircraft for run-up. The general information section of
the applicable MIM contains information concerning
the exhaust area hazards. These instructions should be
strictly followed. No one should foolishly
experiment with the specified safety margins.
After engine operation, no work should be done to
the exhaust section for AT LEAST ONE-HALF
HOUR (preferably longer). If work is necessary
immediately, you must wear leather gloves.
Jet engines produce noise capable of causing
temporary as well as permanent loss of high-frequency
hearing. When working around jet engines, you should
take the following precautions to protect your hearing:
Wear the proper ear protection (ear plugs or
sound attenuators and sometimes both).
Do not exceed the time limits on exposure to the
various sound intensities.
Have periodic checks on your hearing ability.
Engine noise is broadcast from the aircraft in
patterns, which vary in direction, distance, and
intensity with engine speed. The most intense sound
areas are in the shape of two lobes extending out and
aft from the aircraft center line. However, dangerous
intensities are also present to the side and forward of
the aircraft. (See fig. 5-13) This information is found
in the applicable Naval Air Training and Operating
Procedures Standardization (NATOPS) manual.
Damage to hearing occurs when the ear is exposed
to high sound intensities for excessive periods. The
higher the sound intensity, the shorter the period of
exposure that will produce damage. Above 140 decibel
(dB) sound intensity, any exposure without ear
protection can cause damage.
NOTE: Sound intensity is measured in decibels
(dB). A dB is a number that relates a given sound
intensity to the smallest intensity that the average
person can hear.
By wearing regulation earplugs or sound
attenuators, you can raise the limits of time exposure.
Personnel working within danger areas should be
familiar with calculated noise dB levels (as specified
in the applicable MIM), and should wear the necessary
According to many insurance companies, what
is considered the most dangerous environment in
When you work around aircraft with propellers,
when is it safe to walk through or stand in the
Does a protective screen over the inlet of an
operating aircraft engine eliminate the
possibility of serious injury?
What are the two major hazards of jet engine
Any exposure, without ear protection, can cause
hearing damage above what decibel (dB) level?
Movable Surface Hazards
Moveable surfaces, such as flight control surfaces,
speed brakes, power-operated canopies, and landing
gear doors, are a major hazard to flight line personnel.
These units are normally operated during ground