17.7 propellor storage and preservation

Question 1

what must propellors be protected against which are taken out of service?

Answer 1

corrosion
foreign debris ingress
moisture

Question 2

if a a propellor is installed which documents give storage information?

Answer 2

AMM aircraft maintenance manual

Question 3

if a propellor is not installed where is storage information found?

Answer 3

PMM propellor maintenance manual

Question 4

what are the storage periods for propellers?

Answer 4

3 months - short-term
6 months - long-term
12 months - long-term
3 years - long-term

Question 5

how must wooden installed propellors be cared for?

Answer 5

clean condition and inspected at regular intervals

Question 6

when stored up to 3 months what must be ensured for wooden propellors?

Answer 6

-they must be placed in a horizontal position to ensure even moisture distribution
- cleaned with a mild solution of soap
-any degradation in surface Finish must be restored to prevent moisture ingress
-blades must be adequately ventilated
-if possible storage are should be clean, warm, dry, dark, and well ventilated between 10-20 degrees

Question 7

what must not be done to wooden propellors to prevent rot?

Answer 7

wrapped in anything

Question 8

how does the procedure for metal propellors differ from wooden for up to 6 months?

Answer 8

regular corrosion inspections in addition

Question 9

what must be done to variable pitch propellor mechanisms in 3 month storage?

Answer 9

the mechanism should be operated to circulate oil prior to shut down.
after a ground run it.must be cleaned with a mild soapy solution

Question 10

if a variable pitch mechanisms are to be stored for up to 6 months what must be done?

Answer 10

in excess of 3 months then the pitch change mechanism must be flushed using an inhibiting oil and then covered with waxed paper

All external parts must be treated with lanolin or an approved anti-corrosive treatment and inspected regularly for corrosion.

Question 11

if a wooden propellor has a automatic pitch change mechanism what should be done when stored up to 3 months?

Answer 11

the hub must be filled with oil.
The propeller must be turned every two weeks to ensure that the internal surfaces of the hub are coated with oil.
Regular inspections must be made for signs of deterioration

Question 12

when stored up to 3 months what must be done to metal blades?

Answer 12

stored in an upright position on stands where the hub is supported by a mandrel

The external surfaces of the propeller must be coated with lanolin or an approved corrosion inhibitor. The pitch change mechanism must be drained of oil and flushed with approved inhibiting oil. The pitch change mechanism surface must be coated in lanolin and the mechanism must be wrapped in waxed paper

The oil transfer tubes and the propeller attachment parts must be cleaned, coated in lanolin and wrapped in waxed paper

Question 13

what must be done to wooden blades for storage up to 6 months?

Answer 13

the same as 3 months

Question 14

for metal blades up to 6 months what must be done in addition to the three month procedure?

Answer 14

If the propeller blades have pre-loaded bearings, the blades must be rotated to prevent the bearings from brinelling. This must be carried out at the six months point

Question 15

what must be done for storage up to 12 months but longer than 6?

Answer 15

for pre-loaded blades, the blades require exercising after six months and nine months. At twelve months, the bearings must be removed and visually examined for signs of ‘brinelling’ and corrosion. If satisfactory, the bearings must be cleaned, greased and reassembled on to the blades. The propeller must then be re-inhibited and re-protected

Question 16

what must be done for storage over 12 months?

Answer 16

the blades require exercising at the six months and the nine months stage, followed by bearing removal and inspection at the twelve months point. The propeller requires re-inhibiting at each twelve months point. At the three year stage the propeller must be sent for overhaul.

Question 17

if a blade is stored in its original packaging after 12 months what does not need to be done?

Answer 17

it does not require re-inhibiting every twelve months. However, if the blade bearings are in a pre-loaded condition, they are still subject to the requirement for exercising at the six month and nine month periods each year and the annual dismantling and inspection procedure

Question 18

if stored in original packaging what must occur at the 3 year point?

Answer 18

overhaul

Question 19

for all propellor parts stored in waxed paper and packed into an approved crate what must it be labeled with?

Answer 19

-The propeller type and serial number
-Component part numbers
-The modification standard
-Original date of preservation
-The dates of the blade bearing exercise and inspections if applicable