3FS 90, FS 90 R
English / USA
Because a trimmer/
brushcutter is a high-
speed, fast-cutting power 
tool sometimes equipped 
with sharp cutting blades, 
special safety precautions 
must be observed to reduce the risk of 
personal injury.
It is important that you 
read, fully understand and 
observe the following 
safety precautions and 
warnings. Read the 
instruction manual and 
the safety precautions periodically. 
Careless or improper use may cause 
serious or fatal injury.
The terminology utilized in this manual 
when referring to the power tool reflects 
the fact that different types of cutting 
attachments may be mounted on it. The 
term "trimmer" is used to designate an 
FS unit that is equipped with a nylon line 
head or a head with flexible plastic 
blades (i.e., the PolyCut head). A 
"brushcutter" designates a unit 
equipped with a rigid metal blade. Many 
FS models may be used as either a 
trimmer or a brushcutter - therefore, the 
power tool is referred in this manual as a 
"trimmer/brushcutter." Some smaller 
and/or lightweight FS models may only 
be used as a trimmer, i.e., they may not 
be used with metal blades. 
The term "clearing saw" indicates a 
high-powered trimmer/brushcutter that 
is particularly suited for use with a 
circular saw blade to clear saplings or 
small trees. FS models with an "R" on 
the nameplate were originally 
configured (at the time of distribution) as 
a trimmer with a loop handle.
!Warning
As more fully explained later in these 
Safety Precautions, to reduce the risk of 
personal injury, make sure your unit is 
equipped with the proper handle, 
harness and deflector for the type of 
cutting attachment you are using. Use 
only cutting attachments that are 
specifically authorized by STIHL for use 
on your FS model.
Have your STIHL dealer show you how 
to operate your power tool. Observe all 
applicable local safety regulations, 
standards and ordinances.
!Warning!
Do not lend or rent your power tool 
without the instruction manual. Be sure 
that anyone using it understands the 
information contained in this manual.
!Warning!
The use of this machine may be 
hazardous. If the rotating line or blade 
comes in contact with your body, it will 
cut you. When it comes in contact with 
solid foreign objects such as rocks or 
bits of metal, it may fling them directly or 
by ricochet in the direction of bystanders 
or the operator. Striking such objects 
could damage the cutting attachment 
and may cause blades to crack, chip or 
break. Thrown objects, including broken 
heads or blades, may result in serious or 
fatal injury to the operator or bystanders.
STIHL does not recommend the use of 
rigid blades when cutting in stony areas. 
Use your trimmer/brushcutter equipped 
with the appropriate cutting attachment 
only for cutting grass, brush, wood and 
similar material. It must not be used for 
any other purposes, since such misuse 
may result in an accident or damage to 
the machine. 
!Warning!
Minors should never be allowed to use 
this power tool. Bystanders, especially 
children, and animals should not be 
allowed in the area where it is in use.
Safety Precautions and 
Working Techniques