Schempp-Hirth Flugzeugbau GmbH Krebenstraße 25 – Postfach 14 43

D-7312 Kirchheim unter Teck

Maintenance Manual for the powered sailplane model

Discus bT Edition: October 1989

Revision: 8, January 2011

This manual relates to the powered sailplane “Discus bT”

Registr.-No. :

Serial-No. :

Manufacturer : Schempp-Hirth Flugzeugbau GmbH

Owner :

The translation of this manual has been done by best knowledge and judgment, In any case of doubt the original text in German language is authoritative.

SCHEMPP-HIRTH FLUGZEUGBAU GMBH, KIRCHHEIM/TECK

Discus bT MAINTENANCE MANUAL issue October 1989 0.1 Record of revisions Rev. No.

Reference / short title Page Date

6.

Replacing propeller/hub assembly

0.2.1 0.2.2 5.5.1 5.5.2

March 2003

7.

Supplement of equipment and instruments

0.2.3 7.1 7.2.1 7.2.2 7.2.3 7.2.4

December 2006

8.

Technical Note 863-21 Engine pylon

0.2.2 0.2.4 5.11 5.12.1 5.12.2 12.9 13.1 Troubleshooting page 5

January 2011

Note: Cross out revisions which are not included. The list of effective pages must be amended by hand if necessary.

0.1.2

SCHEMPP-HIRTH FLUGZEUGBAU GmbH., KIRCHHEIM/TECK

Discus bT MAINTENANCE MANUAL 5.1.1 Removing the power plant

Drain all fuel and, if installed, remove upper auxiliary tank

Remove power plant battery from fuselage nose

Pull off fuel line and impulse line from fuel pump

Detach engine wiring (by disconnecting 3 wires from terminal block inside

the engine compartment – the yellow/green center wire is the ground connection)

Remove cable ties securing the wiring

Remove decompression valve interconnecting link (see picture on page

5.12.2), remove pylon-mounted valve actuating lever

Remove the nuts from the four bolts attaching the engine to the pylon (see pictures on page 5.12.2)

Lift engine (with prop.) free from the pylon fork.

January 2011 TN 863-21 Revision 8 MB 863-1 5.11

SCHEMPP-HIRTH FLUGZEUGBAU GmbH., KIRCHHEIM/TECK

Discus bT MAINTENANCE MANUAL 5.12 Re-installation of the power plant

Slide down engine (folding prop. mounted) onto the pylon fork, together with the rubber engine shock mounts (vibration isolators, two per each lug).

Tighten engine mounting nuts such that the spacing between the rubber shock mounts is as follows (see also picture on page 5.12.2): Upper shock mounts: 26.5 ± 0.5 mm (1.04 ± 0.02 in.)

Secure upper engine mounting nuts with a cotter pin

Install and tighten lower stop nuts

Re-connect engine wiring Re-connect fuel line and impulse line to fuel pump

Attach wiring and lines to pylon (using cable ties as before)

Mount metal link connecting the decompression valves (see picture on

page 5.12.2), mount valve actuating lever

Carry out an inspection according to section 4.3 b) of the Flight Manual Re-install power plant battery into fuselage nose section

If desired, the upper auxiliary fuel tank (option) may now be re-installed

Note: The materials necessary for re-installing the power plant may be obtained from Schempp-Hirth.

January 2011 TN 863-21 Revision 8 MB 863-1 5.12.1

SCHEMPP-HIRTH FLUGZEUGBAU GmbH., KIRCHHEIM/TECK

Discus bT MAINTENANCE MANUAL Pictures for power plant removal and re-installation

January 2011 TN 863-21 Revision 8 5.12.2

M03

RT

841

January2011

Techn.

Note

No.

863-21

Maintenance

Manual

Diagram

9 12.9

SCHEMPP-HIRTH FLUGZEUGBAU GmbH., KIRCHHEIM/TECK Discus bT MAINTENANCE MANUAL CHECK LIST Registr.: ..............................

Ser.-No.: .............................

Date: ..................................

I. Engine mount (pylon) and pivoting mechanism ITEM TO BE

INSPECTED

KIND OF INSPECTION

FINDINGS 1.1 Engine mount (pylon)

and pivot shaft Check steel tube pylon for cracks, check shaft suspension for proper condition.

1.2 Spindle drive Check for play and proper function, check attachment of its lower moun- ting bracket, check limit switches and their mounts for proper attachment and condition.

1.3 Gas strut Disconnect spindle drive and check that the weight of the power plant is about counterbalanced by the gas strut while pylon swings up and down.

1.4 Arresting wires Check steel cables and NICOPRESS sleeves for proper condition. Check tension: With power plant fully extended, cables must be equally taut. Check that cable retaining springs are hooked up.

1.5 Engine stop block Check that retracted power plant rests firmly against its stop block at the bottom of the engine compartment. Rubber pad firmly adhering to stop block?

1.6 Engine suspension o Check for proper spacing of the annular rubber engine shock mounts (vibration isolators).

o Check condition of rubber elements on lower engine suspension

o Check condition of rubber stops (O-rings) at the pylon

1.7 Diaphragm fuel pump Check that the fuel pump is clear from engine doors while pylon swings up and down.

1.8 Engine door actuating mechanism

Check linkage for free movement, check for low friction in the system.

1.9 Engine doors and door hinges

Check for damage and proper fit. With power plant retracted, check travel of spring on door actuating rods.

1.10 Decompression valve control

When releasing the “DECO” handle, the bellcrank on the pylon must return to its stop so that a gap of at least 3 mm (0.12 in.) exists between the metal link on the decompression valves and the bellcrank. With the “DECO” handle pulled fully back, the prop must rotate with ease.

1.11 General Check that all power plant accessories, wires, lines etc. are properly connected and secured. Check that cables , wires and lines do not get caught while power plant ex tends/retracts.

January 2011 Revision 8 TN 863-21 13.1

TRO

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P

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III. P

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EN

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1.

Eng

ine

mou

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o w

eak

a) R

ubbe

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ount

s at

upp

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ngin

e m

ount

ing

not

tight

ened

pro

perly

b)

Rub

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lem

ents

at t

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wer

eng

ine

mou

ntin

g lo

ose

or

brok

en

a) T

ight

en c

aste

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d nu

t to

the

corr

ect d

ista

nce

and

secu

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with

a c

otte

r pin

C

orre

ct d

ista

nce

betw

een

oute

r edg

es o

f sho

ck m

ount

s:

26.5

± 0

.5 m

m (1

.04

± 0.

02 in

.) b)

Tig

hten

nut

s or

repl

ace

rubb

er e

lem

ents

2. P

lay

in th

e py

lon

susp

ensi

on

1.

Axi

al p

lay

of th

e pi

vot s

haft

caus

ed b

y de

fect

ive

ba

ll be

arin

gs o

r by

bear

ings

dis

plac

ed s

idew

ays

- R

emov

e en

gine

and

(upp

er) f

uel t

ankp

ower

pla

nt

- R

emov

e el

ectri

cal s

pind

le d

rive

- R

emov

e ga

s st

rut

- R

emov

e py

lon

pivo

ting

shaf

t by

1. R

emov

ing

the

two

outm

ost b

olts

“M4”

and

2. P

ress

ing

the

two

spig

ots

inw

ards

into

piv

otin

g sh

aft

us

ing

a bo

lt “M

8”.

- C

heck

spi

got b

earin

gs fo

r pro

per c

ondi

tion.

If ne

cess

ary,

repl

ace

bear

ings

and

/or

re

tain

ing

clip

s.

2.

Rub

ber s

hock

mou

nts

defe

ctiv

e

or

engi

ne m

ount

ing

brok

en

R

epla

ce d

efec

tive

shoc

k m

ount

(s)

or

repl

ace

engi

ne m

ount

ing

brac

ket