# Textron Aviation Multi-Engine Mandatory Service Letter MEL-57-01: No revision named

- Rights: © Textron Aviation Inc. Filed by the FAA in regulations.gov docket FAA-2018-0068; AD 2018-03-03, 2018-03-03 R1 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Textron Aviation Multi-Engine Mandatory Service Letter MEL-57-01](https://openairdocs.org/service-documents/cessna/mel57-01.md)
- Title as filed: mel-57-01
- Pages: 14
- PDF: https://openairdocs.org/files/sha256/20/63/2063f761344eedf1072293af4e176d2ca47fa1c5ad9c2af40d740226c3712d6d
- Page: https://openairdocs.org/service-documents/cessna/mel57-01/file/2063f761344e

## Text

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### Page 1

Multi
-
engine
SER
VICE
LETTER
MANDA
T
OR
Y
MEL
-
57
-
01
TITLE
WINGS
-
FOR
W
ARD
LOWER
SP
AR
CAP
INSPECTION
EFFECTIVITY
This
service
letter
applies
to
the
models
and
serials
that
have
15
,
000
or
more
flight
hours
as
follows
MODEL
SERIAL
NUMBERS
401
401
-
0001
thru
401
-
0322
401A
401A0001
thru
401A0132
401B
401B0001
thru
401B0221
402
402
-
0001
thru
402
-
0322
402A
402A0001
thru
402A0129
402B
402B0001
thru
402B1384
402C
689
,
402C0001
thru
402C1020
41
1
41
1
-
0001
thru
41
1
-
0250
41
1A
41
1
-
0251
thru
41
1
-
0300
414
414
-
0001
thru
414
-
0965
414A
414A0001
thru
414A1212
421
421
-
0001
thru
421
-
0200
421A
421A0001
thru
421A0158
This
service
letter
applies
to
the
models
and
serials
that
have
12
,
000
or
more
flight
hours
as
follows
MODEL
SERIAL
NUMBERS
421B
421B0001
thru
421B0970
421C
421C0001
thru
421C1807
REASON
Cracks
have
been
found
in
the
forward
lower
carry
through
spar
cap.
An
undetected
crack
can
cause
the
spar
cap
to
break
which
could
result
in
flight
instability
and
potential
loss
of
control.
DESCRIPTION
This
service
document
provides
instructions
to
complete
an
initial
and
recurring
detailed
visual
inspection
of
the
forward
spar
,
lower
carry
through
spar
cap.
The
detailed
visual
inspection
is
of
the
bottom
surface
of
the
carry
through
spar
cap
in
the
area
around
the
fasteners
located
just
inboard
,
of
the
left
and
right
,
forward
lower
wing
fitting.
A
surface
eddy
current
inspection
will
be
necessary
if
a
crack
is
suspected.
W
ARNING:
Further
flight
with
a
cracked
carry
through
spar
cap
is
prohibited.
The
carry
through
spar
cap
must
be
replaced
before
further
flight.
NOTE:
In
order
to
reduce
possible
damage
to
the
structure
,
it
is
recommended
that
the
access
panels
be
installed
with
MEB
-
57
-
01
,
MEB
-
57
-
02
,
SK402
-
49
or
SK421
-
152.
MEL
-
57
-
01
December
18
,
2017
Page
1
of
9
T
extron
A
viation
Customer
Service
,
P
.O.
Box
7706
,
Wichita
,
KS
67277
,
U.S.A.
1
-
316
-
517
-
5800
This
document
contains
technical
data
and
is
subject
to
U.S.
export
regulations.
This
information
has
been
exported
from
the
United
States
in
accordance
with
export
administration
regulations.
Diversion
contrary
to
U.S.
law
is
prohibited.
ECCN:
9E991
COPYRIGHT
©
2017

### Page 2

MEL
-
57
-
01
Page
2
December
18
,
2017
Multi
-
engine
SER
VICE
LETTER
MANDA
T
OR
Y
MEL
-
57
-
01
COMPLIANCE
MANDA
T
OR
Y
.
This
service
document
must
be
accomplished
as
follows:
Model
W
ith
Flight
Hours
Of
Flight
Hours
T
o
Comply
W
ith
Initial
Inspection
Flight
Hours
For
Recurring
Inspection
Interval
All
Airplanes
25
,
000
or
more
25
Flight
Hours
Every
50
Flight
Hours
421B
,
421C
12
,
000
thru
24
,
999
50
Flight
Hours
Every
50
Flight
Hours
401
,
401A
,
401B
,
402
,
402A
,
402B
,
402C
,
41
1
,
41
1A
,
414
,
414A
,
421
,
421A
15
,
000
thru
24
,
999
50
Flight
Hours
Every
50
Flight
Hours
NOTE:
Airplanes
that
have
less
than
the
minimum
required
number
of
flight
hours
upon
receipt
of
this
service
letter
must
comply
with
this
inspection
within
50
flight
hours
of
reaching
the
minimum
flight
hours
listed
in
the
above
table.
A
service
document
published
by
T
extron
A
viation
may
be
recorded
as
completed
in
an
aircraft
log
only
when
the
following
requirements
are
satisfied:
1)
The
mechanic
must
complete
all
of
the
instructions
in
the
service
document
,
including
the
intent
therein.
2)
The
mechanic
must
correctly
use
and
install
all
applicable
parts
supplied
with
the
service
document
kit.
Only
with
written
authorization
from
T
extron
A
viation
can
substitute
parts
or
rebuilt
parts
be
used
to
replace
new
parts.
3)
The
mechanic
or
airplane
owner
must
use
the
technical
data
in
the
service
document
only
as
approved
and
published.
4)
The
mechanic
or
airplane
owner
must
apply
the
information
in
the
service
document
only
to
aircraft
serial
numbers
identified
in
the
Effectivity
section
of
the
document.
5)
The
mechanic
or
airplane
owner
must
use
maintenance
practices
that
are
identified
as
acceptable
standard
practices
in
the
aviation
industry
and
governmental
regulations.
No
individual
or
corporate
organization
other
than
T
extron
A
viation
is
authorized
to
make
or
apply
any
changes
to
a
T
extron
A
viation
-
issued
service
document
or
flight
manual
supplement
without
prior
written
consent
from
T
extron
A
viation.
T
extron
A
viation
is
not
responsible
for
the
quality
of
maintenance
performed
to
comply
with
this
document
,
unless
the
maintenance
is
accomplished
at
a
T
extron
A
viation
-
owned
Service
Center
.
CONSUMABLE
MA
TERIAL
Y
ou
must
use
the
consumable
materials
that
follow
,
or
their
equivalent
,
to
complete
this
service
document.
NAME
NUMBER
MANUF
ACTURER
USE
Rivet
MS20426AD4
Commercially
A
vailable
For
skin
panel
installation
,
various
lengths
determined
at
time
of
installation.
Rivet
MS20470AD4
Commercially
A
vailable
For
skin
panel
installation
,
various
lengths
determined
at
time
of
installation.

### Page 3

Multi
-
engine
SER
VICE
LETTER
MANDA
T
OR
Y
MEL
-
57
-
01
T
OOLING
NAME
NUMBER
MANUF
ACTURER
USE
10X
Magnifying
Lens
Commercially
A
vailable
For
detailed
visual
inspection
of
forward
spar
cap
REFERENCES
Cessna
Model
401
and
402
(1967
-
1978)
Service
Manual
Cessna
Model
402C
(1979
-
1985)
Maintenance
Manual
Cessna
Model
41
1
/
41
1A
(1965
-
1968)
Service
Manual
Cessna
Model
414
/
414A
(1970
-
1985)
Service
Manual
Cessna
Model
421
,
421A
,
421B
Series
(1968
-
1975)
Service
Manual
Cessna
Model
421C
(1976
-
1985)
Service
Manual
NOTE:
T
o
make
sure
all
publications
used
are
complete
and
current.
Refer
to
www
.txtavsupport.com.
PUBLICA
TIONS
AFFECTED
None
ACCOMPLISHMENT
INSTRUCTIONS
1.
Prepare
the
airplane
for
maintenance.
A.
Make
sure
that
the
airplane
is
electrically
grounded.
B.
Make
sure
that
all
switches
are
in
the
OFF
/
NORM
position.
C.
Disconnect
electrical
power
from
the
airplane.
(1)
Disconnect
the
airplane
battery
.
(2)
Disconnect
external
electrical
power
.
D.
Attach
maintenance
warning
tags
to
the
battery
and
external
power
receptacle
that
have
"DO
NOT
CONNECT
ELECTRICAL
POWER
-
MAINTENANCE
IN
PROGRESS"
written
on
them.
2.
Remove
access
panels
as
follows:
NOTE:
Forward
spar
access
panels
were
installed
with
service
bulletins
MEB
-
57
-
01
or
MEB
-
57
-
02
-
Access
Panel
Installation
for
Forward
Spar
or
service
kits
SK402
-
49
,
and
SK421
-
152
-
Access
Panel
Installation
and
Stub
Wing
Fitting
Removal
/
Installation.
These
panels
are
directly
below
the
forward
spar
wing
fitting.
•
Model
401
and
402
series
airplanes
remove
panels
32
and
94.
(Refer
to
the
Model
401
and
402
(1967
-
1978)
Service
Manual.)
•
Model
402C
airplanes
remove
panels
51
1AB
,
51
1A
T
,
512BT
,
61
1AB
,
61
1A
T
and
612BT
.
(Refer
to
the
Model
402C
(1979
-
1985)
Maintenance
Manual.)
•
Model
41
1
airplanes
remove
panels
35
and
57.
(Refer
to
the
Model
41
1
/
41
1A
(1965
-
1968)
Service
Manual.)
•
Model
414
airplanes
remove
panels
34
,
35
and
41.
(Refer
to
the
Model
414
/
414A
(1970
-
1985)
Service
Manual.)
•
Model
414A
airplanes
remove
panels
51
1AB
,
51
1A
T
,
512A
T
,
61
1AB
,
61
1A
T
and
612A
T
.
(Refer
to
the
Model
414
/
414A
(1970
-
1985)
Service
Manual.)
•
Model
421
,
421A
,
and
421B
airplanes
remove
panels
35
,
57
and
93.
(Refer
to
the
Model
421
,
421A
,
421B
Series
(1968
-
1975)
Service
Manual.)
MEL
-
57
-
01
December
18
,
2017
Page
3

### Page 4

MEL
-
57
-
01
Page
4
December
18
,
2017
Multi
-
engine
SER
VICE
LETTER
MANDA
T
OR
Y
MEL
-
57
-
01
•
Model
421C
airplanes
remove
panels
51
1AB
,
51
1A
T
,
512A
T
,
61
1AB
,
61
1A
T
and
612A
T
.
(Refer
to
the
Model
421C
(1976
-
1985)
Service
Manual.)
A.
(Airplanes
with
the
forward
spar
access
panels.
Refer
to
Figure
1
,
Detail
A.)
Remove
the
5292032
-
4
or
5292031
-
10
Forward
Spar
Access
Panel
if
installed
with
MEB
-
57
-
01
,
MEB
-
57
-
02
or
SK425
-
49.
NOTE:
Forward
spar
access
panels
were
installed
with
either
service
bulletins
MEB
-
57
-
01
or
MEB
-
57
-
02
-
Access
Panel
Installation
for
Forward
Spar
or
service
kits
SK402
-
49
,
or
SK421
-
152
-
Access
Panel
Installation
and
Stub
Wing
Fitting
Removal
/
Installation.
These
panels
are
directly
below
the
forward
spar
wing
fitting.
B.
(Airplanes
without
the
forward
spar
access
panels.
Refer
to
Figure
1
,
Detail
B.)
Remove
rivets
as
necessary
from
the
left
and
right
lower
stub
wing
skin
suf
ficient
to
get
access
to
the
bottom
surface
of
the
lower
carry
through
spar
cap
for
the
visual
inspection.
CAUTION:
Use
caution
when
removing
fasteners
along
the
two
lateral
rows
of
rivets
just
forward
and
aft
of
the
fitting.
These
two
rows
are
common
to
the
lower
carry
through
spar
web
flanges.
CAUTION:
T
o
prevent
cracking
dimples
or
damaging
understructure
,
when
removing
rivets
from
dimpled
holes
,
drill
a
hole
into
the
rivet
shank
before
driving
it
out.
(1)
Remove
all
rivet
butts
,
drill
shavings
,
and
foreign
object
debris.
3.
Clean
the
lower
surface
of
the
left
and
right
side
of
the
carry
through
spar
cap
as
follows:
A.
Use
a
suitable
solvent
to
remove
all
grease
and
dirt
from
the
lower
spar
cap
area.
B.
W
ash
the
remaining
solvent
of
f
with
soap
and
water
and
let
air
dry
.
4.
(Refer
to
Figure
1
,
Detail
C.)
Do
a
detailed
visual
inspection
of
the
left
and
right
side
of
the
carry
through
spar
cap
as
follows:
NOTE:
A
detailed
inspection
is
described
as
an
intensive
visual
examination
of
a
specific
structural
area
,
system
,
installation
or
assembly
to
detect
damage
,
failure
,
or
irregularity
.
A
vailable
lighting
is
normally
supplemented
with
a
direct
source
of
good
lighting
at
an
intensity
deemed
appropriate
by
the
inspector
.
Inspection
aids
such
as
mirrors
,
magnifying
lenses
,
etc.
may
be
used.
Surface
cleaning
and
elaborate
access
procedures
may
be
required.
A.
Use
a
suitable
light
source
and
a
10X
Magnifying
Lens
to
inspect
the
bottom
surface
of
the
left
and
right
side
of
the
carry
through
spar
cap
inboard
of
the
lower
fittings
in
the
area
extending
1
-
inch
inboard
to
1
-
inch
outboard
of
the
two
rows
of
fasteners
and
around
all
10
fasteners.
W
ARNING:
Further
flight
with
a
cracked
carry
through
spar
cap
is
prohibited.
The
carry
through
spar
cap
must
be
replaced
before
further
flight.
B.
If
a
crack
is
found
,
no
further
flight
is
permitted.
Contact
Cessna
Structures
at:
csstructures@txtav
.com
,
or
phone:
316
-
517
-
6061.
C.
If
an
area
is
questionable
,
do
a
surface
eddy
current
examination
,
go
to
Step
5.
D.
If
no
cracks
or
questionable
areas
are
found
,
go
to
Step
6.
5.
Do
a
surface
eddy
current
examination
of
the
suspect
area
on
the
carry
through
spar
cap.
(For
surface
eddy
current
instructions
refer
to
inspection
documents
listed
below
.)
•
Model
401
and
402
series
airplanes
refer
to
the
Model
401
and
402
(1967
-
1978)
Service
Manual
,
Supplemental
Inspection
Number
57
-
10
-
10
-
Lower
Carry
-
Thru
Main
Spar
Cap
•
Model
402C
airplanes
refer
to
the
Model
402C
(1979
-
1985)
Maintenance
Manual
,
Supplemental
Inspection
Number
57
-
10
-
14
-
Wing
Lower
Carry
-
Thru
Front
Spar
Cap
•
Model
41
1
airplanes
refer
to
the
Model
41
1
/
41
1A
(1965
-
1968)
Service
Manual
,
Supplement
Inspection
Number
57
-
10
-
10
-
Lower
Carry
-
Thru
Main
Spar
Cap
•
Model
414
airplanes
,
refer
to
the
Model
414
/
414A
(1970
-
1985)
Service
Manual
,
Supplement
Inspection
Number
57
-
10
-
10
-
Lower
Carry
-
Thru
Main
Spar
Cap
•
Model
414A
airplanes
,
refer
to
the
Model
414
/
414A
(1970
-
1985)
Service
Manual
,
Supplement
Inspection
Number
57
-
10
-
14
-
Lower
Carry
-
Thru
Front
Spar
Cap

### Page 5

Multi
-
engine
SER
VICE
LETTER
MANDA
T
OR
Y
MEL
-
57
-
01
•
Model
421
,
421A
,
421B
airplanes
,
refer
to
the
Model
421
,
421A
,
421B
Series
(1968
-
1975)
Service
Manual
,
Supplement
Inspection
Number
57
-
10
-
10
-
Lower
Carry
-
Thru
Main
Spar
Cap
•
Model
421C
airplanes
,
refer
to
the
Model
421C
(1976
-
1985)
Service
Manual
,
Supplement
Inspection
Number
57
-
10
-
14
-
Lower
Carry
-
Thru
Front
Spar
Cap
NOTE:
The
eddy
current
technician
must
be
qualified
and
certified
to
Level
2
or
3
per
the
requirements
of
NAS
410
or
equivalent.
A.
If
a
crack
is
found.
Contact
Cessna
Structures
at:
csstructures@txtav
.com
,
or
phone:
316
-
517
-
6061.
6.
Complete
the
attached
INSPECTION
RESUL
TS
FORM
and
return
to
Cessna
Structures
at
csstructures@txtav
.com.
(Refer
to
the
attached
INSPECTION
RESUL
TS
FORM.)
NOTE:
Return
the
INSPECTION
RESUL
TS
FORM
to
Cessna
Structures
even
if
no
crack
is
found.
7.
(Airplanes
without
forward
spar
access
panels.)
Install
MS20426AD4
-
X
and
MS20470AD4
-
X
Rivets
to
secure
the
stub
wing
skin.
NOTE:
Rivet
length
can
vary
,
determine
correct
length
at
time
of
install.
8.
Install
all
removed
access
panels.
9.
Remove
the
maintenance
warning
tags
and
connect
the
airplane
battery
.
10.
Make
a
logbook
entry
that
states
the
recurring
inspection
is
due
at
the
specified
flight
hour
interval
as
listed
in
the
COMPLIANCE
section
of
this
service
letter
.
NOTE:
An
example
of
a
log
book
entry
on
an
airplane
that
currently
has
25
,
500
flight
hours
,
the
next
inspection
is
due
at
25
,
550
flight
hours.
MEL
-
57
-
01
Forward
Lower
Spar
Cap
Inspection
must
be
accomplished
at
or
before
25
,
550
flight
hours.
1
1.
Make
an
entry
in
the
airplane
logbook
that
states
compliance
and
method
of
compliance
with
this
service
document.
MEL
-
57
-
01
December
18
,
2017
Page
5

### Page 6 (OCR)

Beechcraft  Hawker
Multi-engine  SERVICE LETTER  Cessna
TEXTRON ÀVIATION
MANDATORY  MEL-57-01
B21705
Forward Spar
Access Panel
(Reference,
If Installed)
Forward
_ c  Spar Angles
LJ  (Reference)
C
FWD
• OUTBD
DETAIL A
View Looking Up at Forward Spar
Airplanes with Forward Spar Access Panel
NOTE: Model 402 shown for illustrative purposes.
Other models the inspection is in similar location.
A5991T001
Figure 1. Carry Through Spar Cap Inspection (Sheet 1)
MEL-57-01
Page 6  December 18, 2017

### Page 7 (OCR)

Beechcraft  Hawker
Multi-engine  SERVICE LETTER  TEXTRON ÀVIATION  Cessna
MANDATORY  MEL-57-01
B21707
MS20470AD4
Rivets
(Reference)
FWD
MS20426AD4  OUTBD
Rivets
(Reference)
DETAIL B
Airplanes Without Forward Spar Access Panel
NOTE: For airplanes that do not have access panel installed.
The rivet length determined at time of installation.
Figure 1. Carry Through Spar Cap Inspection (Sheet 2)
MEL-57-01
December 18, 2017  Page 7

### Page 8 (OCR)

Beechcraft  Hawker
Multi-engine  SERVICE LETTER  Cessna
TEXTRON ÀVIATION
MANDATORY  MEL-57-01
B21712
Area to Inspect
FWD
OUTBD
DETAIL C
Figure 1. Carry Through Spar Cap Inspection (Sheet 3)
MEL-57-01
Page 8  December 18, 2017

### Page 9

Multi
-
engine
SER
VICE
LETTER
MANDA
T
OR
Y
MEL
-
57
-
01
MA
TERIAL
INFORMA
TION
No
parts
are
required
to
complete
this
service
document.
MEL
-
57
-
01
December
18
,
2017
Page
9

### Page 10

(No text on this page.)

### Page 11

Multi
-
engine
A
TT
ACHMENT
MANDA
T
OR
Y
MEL
-
57
-
01
SP
AR
CAP
INSPECTION
RESUL
TS
FORM
Airplane
Model
Number
Airplane
Serial
Number
T
otal
Airframe
Hours
Left
Engine
Hours
Forward
Lower
Spar
Cap
Hours
Right
Engine
Hours
Owner's
Name
Inspection
Facility
Name
Owner's
address
Inspection
Facility
Address
List
all
STC
installed
on
the
airplane
In
the
table
that
follows
please
provide
detailed
and
dimensioned
descriptions
of
any
crack(s).
Attach
pictures
to
this
form
as
necessary
.

### Page 12

Multi
-
engine
A
TT
ACHMENT
MANDA
T
OR
Y
MEL
-
57
-
01
SP
AR
CAP
INSPECTION
RESUL
TS
FORM
CONTINUED
W
as
a
crack
found:
Y
es
/
No?
Detailed
description:
(Attach
pictures
and
additional
details
as
necessary
,
if
a
crack
was
found
with
visual
inspection
or
with
a
surface
eddy
current
inspection?)
Send
completed
form
/
attachments
to
Cessna
Structures
at
csstructures@txtav
.com

### Page 13

Multi
-
engine
OWNER
ADVISOR
Y
MEL
-
57
-
01
TITLE
WINGS
-
FOR
W
ARD
LOWER
SP
AR
CAP
INSPECTION
T
O:
Cessna
Model
401
,
401A
,
401B
,
402
,
402A
,
402B
,
402C
,
41
1
,
41
1A
,
414
,
414A
,
421
,
421A
,
421B
,
421C
Aircraft
Owner
REASON
Cracks
have
been
found
in
the
forward
lower
carry
through
spar
cap.
An
undetected
crack
can
cause
the
spar
cap
to
break
which
could
result
in
flight
instability
and
potential
loss
of
control.
COMPLIANCE
MANDA
T
OR
Y
.
This
service
document
must
be
accomplished
as
follows:
Model
W
ith
Flight
Hours
Of
Flight
Hours
T
o
Comply
W
ith
Initial
Inspection
Flight
Hours
For
Recurring
Inspection
Interval
All
Airplanes
25
,
000
or
more
25
Flight
Hours
Every
50
Flight
Hours
421
,
421A
,
421B
,
421C
12
,
000
thru
24
,
999
50
Flight
Hours
Every
50
Flight
Hours
401
,
401A
,
401B
,
402
,
402A
,
402B
,
402C
,
41
1
,
41
1A
,
414
,
414A
15
,
000
thru
24
,
999
50
Flight
Hours
Every
50
Flight
Hours
NOTE:
Airplanes
that
have
less
than
the
minimum
required
number
of
flight
hours
upon
receipt
of
this
service
letter
must
comply
with
this
inspection
within
50
flight
hours
of
reaching
the
minimum
flight
hours
listed
in
the
above
table.
MA
TERIAL
A
V
AILABILITY
No
parts
are
required
to
complete
this
service
document.
W
ARRANTY
None
NOTE:
As
a
convenience
,
service
documents
are
now
available
online
to
all
our
customers
through
a
simple
,
free
-
of
-
charge
registration
process.
If
you
would
like
to
sign
up
,
please
visit
the
Customer
Access
link
at
www
.txtavsupport.com
to
register
.
MEL
-
57
-
01
December
18
,
2017
Page
1
of
1
T
extron
A
viation
Customer
Service
,
P
.O.
Box
7706
,
Wichita
,
KS
67277
,
U.S.A.
1
-
316
-
517
-
5800
This
document
contains
technical
data
and
is
subject
to
U.S.
export
regulations.
This
information
has
been
exported
from
the
United
States
in
accordance
with
export
administration
regulations.
Diversion
contrary
to
U.S.
law
is
prohibited.
ECCN:
9E991
COPYRIGHT
©
2017

### Page 14

(No text on this page.)

---
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