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Author Topic: Gipsy Major 10 maintenance  (Read 339 times)

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Offline john henderson

  • Posts: 276
  • Country: gb
Gipsy Major 10 maintenance
« on: Saturday October 06, 2018, 11:41:30 UTC »
Hi all
 in view of the current correspondence on Carol's chipmunk face book group, I am posting here the summary of what the good book says.  We pretty much adhere to what's staged below, but change the engine oil and do the 100 hour items annually as it takes us 2 to three years to do 100 hours.
Any thoughts, comments or variance recommendations?

GYPSY MAJOR 10 MAINTENANCE SCHEDULE – copied May 2017 from the de Havilland Gipsy Major series 10 operation, maintenance and overhaul handbook Sept 1963, chapter VII page 17 – maintenance schedule

Every 50 hours

1.   Clean down engine
2.   Inspect and check magneto contact points
3.   Check all LT and HT connections are secure
4.   Examine and clean oil scavenge filters - see comment below
5.   Turn handle of Autoclean filter - see comment below
6.   Examine and clean fuel pump filters - see comment below
7.   Inspect all oil, fuel and gas connectors
8.   Inspect exhaust manifold for burns or cracking
9.   Lubricate all joints, cables and bearings in the engine control linkwork, including the spindle on the flame trap valve and examine for serviceability and operation
10.   Inspect the propeller for signs of looseness or damage

Every 100 hours do above and in addition

1.   Check cylinder head nuts for tightness. One nut should not be tightened more than another
2.   Remove valve gear covers and examine the valve springs for serviceability, without removing the latter
3.   Check the rocker bracket bolts for tightness and check the tappet clearances and adjust if necessary
4.   Clean the rocker covers and refill with fresh oil to the level of the collar on the vent pipe
5.   Remove all 8 sparking plugs and clean, test and reset the gap
6.   Drain the oil tank and refill with fresh oil - see comment below
7.   Check all exhaust and induction manifold nuts for tightness.
8.   Check the security of all accessories, the carburettor and fuel pumps and also their respective wiring or pipelines.
9.   Examine the engine bearer arms for security, and ensure that the rubber mountings are in good condition
10.   Remove the distributer and clean and check the condition of the HT pick-up brush – see chapter XV page 4
11.   Remove the contact breakers, recondition as necessary and lubricate - see chapter XV page 5
12.   Lubricate the impulse starter - see chapter XV page 5

Every 300 hours do above and in addition

1.   Remove and clean the Autoclean pressure filter and clean out the sediment from the body - see comment below
2.   Inspect and if necessary clean out the flame trap
3.   Examine the magneto flexible couplings for deterioration and oil soakage
4.   Clean the magneto HT pick up slip rings and the flange mountings - see chapter XV page 4
5.   Examine the insulation of the LT cables.


1.   No reference to cleaning primary fuel filter on the bulkhead –suggest every 100 hours
2.   Autoclean filter only needs turning every 50 hours
3.   Oil filters (not Autoclean) every 50 hours - - suggest with today’s oils every 100 hours
4.   Autoclean removal every 300 hours!
5.   Tappets every 100 hours
6.   Rocker box oil change and engine oil change every 100 hours- suggest engine oil every 100 hours or at 12 months.
7.   Question: what do they mean by the flame trap? is this the carb hot air filter?
8.   Question: what do they mean by LT cables, are they referring to the magneto switch feeds
9.     Note We are now on automotive plugs, we re-gap at 50 hours and replace at 100 hours.
john h

Offline Dick Gower

  • Posts: 302
  • Country: au
Re: Gipsy Major 10 maintenance
« Reply #1 on: Sunday October 07, 2018, 20:41:17 UTC »
The filter is referred to as a flame trap elsewhere John, I think in some pilot notes.
Yes, the LT cables would be the P leads to the mag. switches.
Interesting that the autoclean filter is only turned every 50 hours.  Common practice in Oz has been daily which is in common with the RAAF practice on the Tiger.
Dick Gower

Offline john henderson

  • Posts: 276
  • Country: gb
Re: Gipsy Major 10 maintenance
« Reply #2 on: Tuesday October 09, 2018, 09:58:00 UTC »
Thanks Dick, as ever you are most informative. I too am slightly puzzled about the ideal frequency of turning the autoclean.  Looking at its construction, I cannot see the necessity of constantly rotating it, but every 50 hours is once a year for us. Up to now we have pulled it every couple of years to remove the carbon. Never a great amount there, though.
john h

Offline speedbird1

  • Posts: 549
  • Country: us
Re: Gipsy Major 10 maintenance
« Reply #3 on: Wednesday October 10, 2018, 01:58:21 UTC »

I remember clearly being told rather forcibly to turn the Autoclean every day and do not forget it "lad"!!  And true to this day it gets done!!

Speedbird 1.

Offline Nigel Stevens

  • Moderator
  • Posts: 245
  • Country: fr
Re: Gipsy Major 10 maintenance
« Reply #4 on: Wednesday October 10, 2018, 13:42:00 UTC »
For what's its worth, the autoclean filter was designed and used before detergent oils existed. Depending on the quality of the straight mineral oil, refined from different crude oils, some oils probably resisted oxidation and carbon deposit formation, better than others. In addition different environmental and operational conditions probably meant (mean?) that there was considerable variability in the running temeratures of engines and the amount of oxidation/carbon formation. Having lived my life with detergent oils, (mainly in cars) I am surprised with the speed that the straight mineral oil, which I'm using during the run in process on the Chipmunk engine, has gone black with carbon. I don't think is does any harm to turn the filter, and one turn per day seem enough to me. This is especially true if a non detergent oil is in use. Automatically, I would expect there to be very little visible deposit if a detergent oil is in use, this shows the detergent is doing its job!  Since, as Bob points out, most of the aeroplanes now have a lower annual use, it also makes sense to change the oil on a calendar basis rather than a flying hours basis, since one other objective of the detergent oils is to mop up any corrosive chemicals that are produced by the combustion process. If the aeroplane flies little or not at all during the winter, it also makes sense to time the oil change just before the winter shut down so that fresh detergent oil is coating everything giving a little further protection against condensation based corrosion. So my view is : turn the filter regularly, change the oil and clean out the filters at least annually and be happy there is little deposit!

Offline Tug

  • Posts: 2
Re: Gipsy Major 10 maintenance
« Reply #5 on: Saturday October 13, 2018, 22:01:04 UTC »
Here at Yeovilton we turn the filter after every flight as per the MoD publications.


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