Review and reference information
RESTRICTED
CONFIDEN-
TIAL LET-
TERS OF
INSTRUCT-
ION.
REVIEW AND REFERENCE INFORMATION
A. Purpose:
Confidential letters of instruction
are sent
to this department and to the
units working in the
field for the purpose of acquainting the
mainten-
ance
men with newer methods,
techniques, and in-
formation
concernigg the units on hand. These con-
fidential letters of instruction, better known.
as
C.L.l.,
are confidential and
the
must be treated with
respect due confidential documents.
B. Method of Numbering:
in looking up a confidential letter, one may
find
marked
as follows:
(N) - 41-17A.
In in-
terpreting this marking, one finds that the follow-
ing is true:
The (N) means that the letter refers
to Norden equipment; the 41 means that the letter
1941; the
was received in the Army fischumber i7 received
17 means
letter was
in that fiscal year (fiscal year dates from July
Ist to 30th; the A following
the 17 means that it
is a
supplement to letter number 17 and may
rescind
a part of or add to 41-17.
C.
Confidential letters remain in force until re-
scinded,
corrected or replaced.
C.L.l. with which students
should be familiar
are as follows.
40-3
B-40-12
B-41-2
C-42-24
C-42-28
A-42-18
B-42-30
B-42-31
B-43-5
B-43-12
B-43-13
B-43-20
Interchangeability in airplanes.
interchangeability of sight and
stabilizer.
Type Designation of M-Series
Bombsights.
Interchangeability of Bombsights
in Bombardment Airplanes.
Care of
Bombsights and Allied
Equipment Following Water
Immersion.
Stabilizer Mounting Screws, M-
Series Bombsights.
Modification of Mirror Tilting
Device M-4, M-5. M-6, M-7
Bombsights.
General - Use
and Storage of
Bombsights.
Calibration of Altitude Knob.
Calibration of M-Series Bombsights
Destruction of Confidential Eq-
uipment in Combat Zones.
Discontinuance of Automatic ER-
ection System.
it
that
the
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