MBB HELICOPTERS

MAINTENANCE MANUAL MBB - B0 105

804 DUAL WINDSHIELD WIPER SYSTEM

.Table of Contents

Paragraph Title Page

DESCRIPTION - .........
DUAL WINDSHIELD WIPER SYSTEM 3
TROUBLESHOOTING - DUAL WINDSHIELD WIPER SYSTEM . . . . . . . 4

INSPECTION SCHEDULE - DUAL WINDSHIELD WIPER SYSTEM .... 6

INSPECTION FOR CONDITION - DUAL WINDSHIELD WIPER SYSTEM . . . 7

FUNCTIONAL TEST - DUAL WINDSHIELD WIPER SYSTEM . . . . . . . 7

REMOVAL - DUAL WINDSHIELD WIPER SYSTEM . . . . . . . . . . . 8

INSTALLATION - ....... .
DUAL WINDSHIELD WIPER SYSTEM 9

Replacement - wiper blades . . . . . . . . . . . . . . . . . 11

Adjustment - pressure of blade on windshield . . . . . . . . 12

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804 - 1 DESCRIPTION - DUAL WINDSHIELD WIPER SYSTEM

1. General
The purpose of t h e d u a l windshield wiper system i s t o maintain good
forward v i s i b i l i t y f o r t h e p i l o t i n inclement weather.
The system i s o p e r a t e d by t h e wiper s w i t c h WIPER l o c a t e d on t h e
instrument p a n e l . ON, OFF and PARK p o s i t i o n s can b e s e l e c t e d by t h e WIPER
switch.

Description
The windshield wiper u n i t c o n s i s t s of two c o n v e r t e r s (22, f i g . 804-2) and
a motor ( 1 9 ) . It i s a t t a c h e d by a s u p p o r t i n g frame (24) t o t h e c e n t e r
p o s t and h o r i z o n t a l frame of t h e c a b i n s t r u c t u r e . Two c o n v e r t e r s , each
connected t o t h e motor by a coupling, c o n v e r t t h e r o t a r y motion of t h e
motor t o synchronous o s c i l l a t i n g movements of t h e wiper arms, with t h e
wiper arms moving i n o p p o s i t e d i r e c t i o n s . A cam d r i v e n by t h e motor d r i v e
s h a f t v i a a s p e c i a l g e a r t r a i n , r e g u l a r l y o p e r a t e s a microswitch which i s
a l s o i n s t a l l e d i n t h e motor.
The g e a r r e d u c t i o n i n t h i s cam d r i v e i s i d e n t i c a l t o t h a t i n t h e wiper
converters .
During normal o p e r a t i o n , i . e w i t h t h e wiper s w i t c h i n ON, t h i s r e g u l a r ,
automatic a c t u a t i o n of t h e microswitch does n o t a f f e c t motor o p e r a t i o n .
With t h e wiper s w i t c h i n PARK and t h e 3ME dropping r e s i s t o r now connected
i n series with t h e motor, t h e v o l t a g e a p p l i e d t o t h e motor i s decreased
s o t h a t t h e motor slows down and, a f t e r t h e microswitch a c t u a t e s ,
s t o p s . The wipers come t o rest i n t h e stow p o s i t i o n (see f i g . 804-1).

3. Operation
The system i s o p e r a t i o n a l when t h e PP22 a u x i l i a r y bus i s s u p p l i e d with
power and t h e WIPER c i r c u i t . b r e a k e r i s d e p r e s s e d .
With t h e wiper s w i t c h i n t h e ON p o s i t i o n , power i s s u p p l i e d t o t h e 4ME
motor (see f i g . 804-1). The motor d r i v e s t h e wiper through b o t h
c o n v e r t e r s . The wiper i s switched o f f when t h e wiper switch i s set t o
OFF: P r e s s i n g and h o l d i n g t h e wiper s w i t c h i n t h e PARK p o s i t i o n causes
t h e wiper t o come t o rest i n t h e stow p o s i t i o n .
The WIPER s w i t c h must n o t be h e l d i n PARK f o r more t h a n 3 seconds over a
10-minute p e r i o d because t h e 3ME dropping r e s i s t o r w i l l o v e r h e a t .

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804 - 2 TROUBLESHOOTING - DUAL WINDSHIELD WIPER SYSTEM

General
- Use w i r i n g diagram 804-1 i n t h e Wiring Diagram Manual (WDM) f o r
t r o u b l e s h o o t i n g t h e system.
- Perform t r o u b l e s h o o t i n g u s i n g e x t e r n a l power u n i t .
( B a t t e r y s w i t c h on instrument p a n e l i n BAT OFF/EPU ON p o s i t i o n )
- Check a l l c i r c u i t b r e a k e r s and switches f o r unimpaired mechanical
f u n c t i o n i n g ; check e l e c t r i c a l connection f o r s e c u r i t y .
- Depress 1ME c i r c u i t b r e a k e r on instrument p a n e l .
- I f p a r t s of t h e motor a r e damaged, t h e e n t i r e motor may b e exchanged, o r
r e p a i r e d i n accordance w i t h t h e m a n u f a c t u r e r r s i n s t r u c t i o n s .

No. TROUBLE SYMPTOM PROBABLE CAUSE . CORRECTIVE ACTION

1 Dual wiper system D e f e c t i v e 4ME motor Measure v o l t a g e ; check

f a i l s t o s t a r t when motor f o r c o n t i n u i t y .
power i s a p p l i e d t o Replace d e f e c t i v e motor
e l e c t r i c a l system i n accordance with
and 2ME wiper switch p a r a s 804-6 and 804-7
i s i n ON p o s i t i o n

2ME wiper s w i t c h Check wiper s w i t c h

o r 1ME c i r c u i t and c i r c u i t b r e a k e r
breaker defective f o r c o n t i n u i t y and
replace i f defective
Faulty wiring Check c o n t i n u i t y of
between 2ME wiper w i r i n g . Replace f a u l t y
switch, 1ME c i r c u i t wiring
breaker, and
ground ( b o l t on
instrument p a n e l )
2 Motor runs b u t Converter/coupling Replace c o n v e r t e r / c o u p l i n g
wiper arms do defective i n accordance with
n o t move p a r a s 804-6 and 804-7

Table 804-1 Troubleshooting (1 of 2 )

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TROUBLESHOOTING ( cont inued)

No. TROUBLE SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION

3 Wipers f a i l t o s t o p Cam assembly/park Replace motor i n

i n t h e stow p o s i t i o n l i m i t switch accordance with
although wiper def e c t i v e p a r a s 804-6 and
switch i s i n PARK 804-7

4 Wipers do not r e t u r n Defective 2ME Check wiper switch

t o stow p o s i t i o n wiper switch f o r continuity; replace
although wiper i s defective
switch i s i n PARK
Defective 3ME Measure r e s i s t a n c e ;
dropping r e s i s t o r replace i f defective

Worn brushes i n Replace motor i n

4ME motor accordance with
p a r a s 804-6 and
804-7

Defective bonding Reestablish ground

jumpe r connection

5 Wiper arms o s c i l l a t e Excessive c u r r e n t Worn brushes i n

t o o slowly consumption with motor; replace
motor operating motor i n acco-ance
under f u l l l o a with p a r a s 804-6 and
804-7

Defective coupling Replace coupling

i n accordance with
p a r a s 804-6 and 804-7

6 Motor operates Motor- and Align axes i n

noisily converter axes accordance with
not a l i g n e d para 804-7

7 Wiper blades do Wiper blades Replace wiper

not c l e a r t h e deteriorated o r blades i n accordance
windshield damaged with para 804-8

Tension.on wiper Adjust pressure of

blade t o o low blade on windshield i n
accordance with
Para 804-9
-

Table 804-1 Troubleshooting (2 of 2)

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1 804 - 3 INSPECTION SCHEDULE (refer to Chapter 101)

CHAPTER 804 Revision 18

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804 - 4 INSPECT FOR CONDITION - DUAL WINDSHIELD WIPER SYSTEM

1. I n s p e c t wiper b l a d e s f o r s e c u r i t y , c o n d i t i o n and wear. Replace worn o r
damaged wiper b l a d e s .

2. I n s p e c t wiper arms f o r s e c u r i t y and c o n d i t i o n . I f wiper arms a r e loose,

remove lockwire from clamping screws. Tighten up and lockwire clamping
screws.
3. Check p r e s s u r e of wiper b l a d e on windshield. I f necessary, a d j u s t blade
t e n s i o n i n accordance with Para 804-9.

4. Check stow p o s i t i o n of wiper b l a d e s . I n t h e stow p o s i t i o n t h e wiper

b l a d e s must rest p a r a l l e l t o t h e c e n t e r p o s t of t h e c a b i n s t r u c t u r e . The
c l e a r a n c e between e a c h b l a d e and t h e c e n t e r p o s t should be approx. 30 mm.
I f necessary, c o r r e c t t h e stow p o s i t i o n by r e l o c a t i n g t h e wiper arms on
t h e i r r e s p e c t i v e wiper s h a f t s .

5. I n s p e c t t h e c a s i n g of both c o n v e r t e r s f o r c r a c k s and l o s s of g r e a s e
around t h e wiper s h a f t , worm and housing assembly and Cover p l a t e .
Replace c o n v e r t e r s a s necessary.
6. I n s p e c t wiper d r i v e u n i t f o r s e c u r i t y , c o r r o s i o n , d i s t o r t i o n and damageä
s u r f a c e p r o t e c t i o n . Replace damaged a t t a c h i n g hardware. Touch up damaged
s u r f a c e p r o t e c t i o n and corroded a r e a s .

7. I n s p e c t e l e c t r i c a l c o n n e c t i o n s f o r s e c u r i t y and c o n d i t i o n .

804 - 5 FUNCTIONAL TEST - DUAL WINDSHIELD WIPER SYSTEM

General

CAUT I O N TAKE CARE THAT PILOT AND COPILOT DOORS ARE CLOSED DURING
WIPER OPERATION WITH THE BLADES CLEAR OF WINDSHIELD.

- To e n s u r e smooth o p e r a t i o n of wiper d u r i n g f u n c t i o n a l test, continuously

Spray windshield w i t h water, o r l i f t wiper arm c l e a r of windshield.
- Connect e x t e r n a l power supply. P l a c e b a t t e r y s w i t c h on instrument panel
i n BAT OFFIEPU ON p o s i t i o n . Depress 1ME WIPER c i r c u i t b r e a k e r on
instrument p a n e l .

1. P l a c e 2ME WIPER switcli i n ON p o s i t i o n ; b o t h wipers o s c i l l a t e

synchronously i n o p p o s i t e d i r e c t i o n s . S t o p wiper by moving wiper switch
t o OFF.

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CAUTION D0 NOT HOLD THE 2ME WIPER SWITCH I N THE PARK

POSITION FOR MORE THAN 3 SECONDS OVER A 10-MINUTE PERIOD
BECAUSE THE 3ME DROPPING RESISTOR WILL OVERHEAT.

2. Continue t o h o l d wiper s w i t c h i n PARK p o s i t i o n u n t i l t h e wiper g r a d u a l l y

approaches stow p o s i t i o n and t h e motor s t o p s suddenly a t t h e i n b o a r d end
of t h e s t r o k e .

3. V e r i f y t h a t b o t h wiper b l a d e s a r e p a r a l l e l t o t h e c e n t e r p o s t . Remove
e x t e r n a l power supply.
4. Move b a t t e r y s w i t c h t o BAT ON. I f t h e 2ME wiper s w i t c h i s now p o s i t i o n e d
t o ON, t h e wiper w i 1 . l n o t respond because i n normal system o p e r a t i o n it
w i l l o n l y r e c e i v e power when both g e n e r a t o r s a r e o p e r a t i n g .

5. Switch o f f d u a l wiper system and p l a c e b a t t e r y s w i t c h t o BAT OFF.

804 - 6 REMOVAL - DUAL WINDSHIELD WIPER SYSTEM

1. Wiper arm

a. L i f t wiper arms (13, f i g . 804-2) f a r enough away from t h e windshield

f o r a p i n ( 2 . 5 mrn diameter) t o b e i n s e r t e d i n t o t h e borehole (12) i n
each arm channel t o h o l d them c l e a r of t h e windshield. Operate wiper
t o stow p o s i t i o n .
b. A f t e r removing t h e lockwire, unscrew and remove screw ( 9 ) with washer
(10) from each wiper arm and unscrew t h e r e s p e c t i v e clamping screw
( 7 ) ; d e t a c h wiper arms from wiper s h a f t s .

2. Wiper d r i v e u n i t

a. P u l 1 o u t 1ME c i r c u i t b r e a k e r on i n s t r u m e n t p a n e l .
b. Remove instrument p a n e l f a i r i n g a s f a r a s n e c e s s a r y .
C. Disconnect e l e c t r i c a l connector (23) and bonding jumper ( 3 and 2 0 ) .
d. Remove screws (1,17) from t h e c e n t e r p o s t and h o r i z o n t a l
frame and c a r e f u l l y withdraw t h e d r i v e u n i t w i t h t h e wiper s h a f t s
from t h e lead-throughs i n t h e w i n d s h i e l d .

e. I f r e q u i r e d , remove t h e components of both windshield lead-throughs

a s follows:
Unscrew and remove screws ( 4 ) and washers ( 5 ) . This r e l e a s e s two
washers ( 2 5 ) , two rubber d i s c s (26) and one r e t a i n i n g r i n g ( 2 7 ) .
Remove t h e f o u r d i s t a n c e s l e e v e s ( 6 ) from t h e b o r e h o l e s around t h e
lead-through. ( I n s t a l l a t i o n r e q u i r e s h e l p from an a s s i s t a n t ) .

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3. Motor and c o n v e r t e r s
a. Remove screws (3, f i g . 804-3) with n u t s (1) and washers ( 2 ) and
remove screws (14) with n u t s (16) and washers (15) .

b. Disconnect both c o n v e r t e r s from t h e motor.

C. C a r e f u l l y remove couplings with s p r i n g c l i p s ( 6 ) from t h e connector
sleeves ( 7 ) .

d. Remove screws (11) and washers ( 1 0 ) ; remove b r a c k e t (12) from

motor ( 5 ) .

804 - 7 INSTALLATION - DUAL WINDSHIELD WIPER SYSTEM

1. I n i t i a l s e t t i n g of motor and c o n v e r t e r s .

a. Engage e x t e r n a l power supply.

b. Connect e l e c t r i c a l connector (9, f i g . 804-3) t o motor (5) and make
e l e c t r i c a l bonding connection.

C. Hold motor s o t h a t i t s weight i s n o t s u p p o r t e d by wiring h a r n e s s and

bonding jumper ( 8 ) ; now d e p r e s s 1ME c i r c u i t b r e a k e r on instrument
p a n e l and t h e n h o l d WIPER t o g g l e s w i t c h on instrument p a n e l i n PARK
p o s i t i o n u n t i l t h e motor s t o p s i n t h e stow p o s i t i o n .
d. To p r o c e e d . w i t h i n s t a l l a t i o n , a g a i n d i s c o n n e c t e l e c t r i c a l connector
and bonding jumper from motor.

e. Now a d j u s t both c o n v e r t e r s t o t h e i r r e s p e c t i v e stow p o s i t i o n s by

r o t a t i n g t h e c o n v e r t e r d r i v e s h a f t s u n t i l t h e wiper arms reach t h e
inboard end of t h e i r s t r o k e s . (Note t h a t wiper s h a f t s o s c i l l a t e i n
opposite directions) .

2. Assembling t h e motor and c o n v e r t e r s .

a. I n s t a l l new 0 - r i n g s i n t h e connector s l e e v e s (7, f i g . 804-3).

b. L u b r i c a t e r i g h t and l e f t couplings and a s s o c i a t e d s p r i n g c l i p s ( 6 )

with g r e a s e (CM 1 0 2 ) , and c a r e f u l l y i n s t a l l t h e couplings on t h e i r
respective converter drive shafts.

C. To a v o i d damaging t h e 0-rings, c a r e f u l l y connect t h e c o n v e r t e r s t o

t h e r i g h t and l e f t motor s h a f t s v i a t h e c o u p l i n g s .

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NOTE For a good ground connection, t h e f o l l o w i n g mating s u r f a c e s

must b e f r e e from non-conductive f i n i s h e s :
Wiper motor - b r a c k e t
Converter - s u p p o r t i n g frame
Bracket - s u p p o r t i n g frame
d. Attach b r a c k e t (12) l o o s e l y t o s u p p o r t i n g frame (13) with screws
( 1 4 ) , washers (15) and n u t s ( 1 6 ) .

e. F i t motor and c o n v e r t e r s i n s u p p o r t i n g frame; a t t a c h c o n v e r t e r s t o

s u p p o r t i n g frame w i t h screws ( 3 ) , washers ( 2 ) and n u t s (1); a t t a c h
motor t o b r a c k e t with screws (11) and washers ( 1 0 ) .
f. Make a b s o l u t e l y Sure t h a t t h e axes of t h e motor and c o n v e r t e r s a r e
a l i g n e d when t i g h t e n i n g t h e screws i n s t a l l e d i n s t e p s d . and e .

g. Connect e l e c t r i c a l connector and bonding jumper t o motor; p o s i t i o n

WIPER switch t o ON and check t h a t motor r u n s smoothly. I f motor i s
rough-running, r e a l i g n motor and c o n v e r t e r s .
h. Disconnect e l e c t r i c a l connector and bonding jumper again; apply
l a c q u e r t o any exposed b a r e meta1 s u r f a c e s .
i. Replace removed lockwires.

3. I n s t a l l a t i o n of wiper d r i v e u n i t
a. I f removed, r e - i n s t a l l lead-through components by i n s e r t i n g t h e f o u r
d i s t a n c e s l e e v e s (6, f i g . 804-2) f i r s t . Then h o l d rubber d i s c (26)
and washer (25) c o r r e c t l y a l i g n e d on t h e o u t e r s u r f a c e of t h e wind-
s h i e l d and, w i t h t h e a s s i s t a n t doing l i k e w i s e w i t h rubber d i s c ( 2 6 ) ,
washer (2'5) and r e t a i n i n g r i n g (27) on t h e i n n e r s u r f a c e , i n s t a l l and
handtighten t h e f o u r screws ( 4 ) and washers ( 5 ) .
b. Back o f f two screws (18) and f o u r screws (21) o n l y enough t u r n s t o
allow displacement of t h e r e t a i n i n g b r a c k e t . C a r e f u l l y i n s e r t wiper
s h a f t s through t h e windshield lead-throughs.
C. Loosely a t t a c h s u p p o r t s t r u c t u r e t o c e n t e r p o s t and h o r i z o n t a l
s t r u c t u r e with screws ( 1 7 ) , washers and n u t s , and screws ( I ) , two
washers and n u t s , r e s p e c t i v e l y ; a l i g n s u p p o r t s t r u c t u r e s o t h a t wiper
s h a f t s a r e c o n c e n t r i c with t h e lead-though and provide a t i g h t s e a l
w i t h t h e rubber d i s c s ( 2 6 ) .
d. Tighten screw connections (1, 17, 18, 21) .

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e. Connect bonding jumpers (3, 20) with screws, washers, s p r i n g washers,

and nut s .

f. Connect e l e c t r i c a l connector (23) and i n s t a l l lockwire.

4. I n s t a l l i n g t h e wiper arms.
a. Temporarily i n s t a l l and hold l e f t wiper arm (13, f i g . 804-2) on wiper
s h a f t ; a f t e r removing t h e r e t a i n i n g p i n from borehole (12) i n t h e arm
channel, lower t h e wiper arm with blade onto t h e windshield s o t h a t
t h e wiper blade i s p a r a l l e l t o and approx. 30 mm away from t h e c e n t e r
post.
b. I f necessary, a d j u s t stow p o s i t i o n of wiper blade by loosening nut
(16) and r e p o s i t i o n i n g t h e wiper arm t o give t h e s p e c i f i e d clearance.
Tighten nut (16) and clamping screw ( 7 ) . I n s t a l l screw ( 9 ) with
washer ( 1 0 ) .

C. Repeat s t e p s a . and b . f o r t h e r i g h t wiper arm.

5. Concluding work.
a. Check p r e s s u r e of blade on windshield; i f necessary, a d j u s t tension
on wiper blade ( r e f e r t o Para 804-9).
b. Perform f u n c t i o n a l test ( r e f e r t o Para 804-5).

C. Lockwire screw (9) t o clamping screw (7) .

d. ~ n s t a l l instrument
' panel f a i r i n g .

804 - 8 Replacement - wiper blades

1. L i f t wiper arms (13, f i g . 804-2) from t h e i r stow p o s i t i o n s and hold them
c l e a r of windshield by i n s e r t i n g a p i n (2.5 mm diameter) i n borehole (12)
i n each arm channel.
2. Remove nut (16) with washer and detach wiper blade.

3. I n s e r t new wiper blade and p o s i t i o n i t p a r a l l e l t o and approx. 30 mm away

from t h e c e n t e r p o s t .

4. Secure wiper blade t o wiper arm with nut and washer ( 1 6 ) .

5. Remove p i n and lower t h e wiper blade onto t h e windshield; r e a l i g n wiper

blade i f it i s not p a r a l l e l t o t h e c e n t e r p ~ s t .

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804 - 9 Adjustment - pressure of b l a d e on w i n d s h i e l d

1. Attach s p r i n g s c a l e t o measuring p o i n t ( f i g . 804-2) on wiper arm.

2.. The wiper b l a d e must d e t a c h from t h e w i n d s h i e l d w i t h a p u l l i n g f o r c e of

15-17 N. I f necessary, a d j u s t p r e s s u r e of b l a d e on windshield a s f o l l o w s :

- To d e c r e a s e t e n s i o n on blade, t u r n p r e s s u r e a d j u s t i n g screw (11)

clockwise.
- To i n c r e a s e t e n s i o n on blade, t u r n p r e s s u r e a d j u s t i n g screw (11)
counterclockwise.

3. Operate wiper f o r one minute on a wet w i n d s h i e l d and t h e n check b l a d e

tension; readjust blade tension a s necessary.

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MAINTENANCE MANUAL MBB - B0 105

INSTRUMENT PANEL 2VE !

I
304-18 - i
i
I
I I
2VEd
I I I

NC switch shown i n park p o c i t i o n

Fig. 804-1 Dual windshield wiper system - Wiring Diagram

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/\ Blade pressure measuring point

Screw free
Center post Nut, washer
Bonding jumper Screw
Screw Screw
Washer Motor
Distance sleeve Bonding jumper
Clamping screw Screw
Lockwire Converter
Screw Electrical connector
Washer Supporting frame
Pressure adjusting Washer
screw Rubber disc
Borehole Retaining ring
Wiper arm
Wiper blade

Fig. 804-2 Dual windshield wiper system

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Nut E l e c t r i c a l connector
Washer Washer
Screw Screw
Converter Bracket
Motor Supporting frame
Coupling with s p r i n g c l i p Screw
Connector s l e e v e Washer
Bonding jumper Nut

F i g . 804-3 Windshield wiper a g g r e g a t e

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