C-GZHQ Engine
Currently the engine is at 1125 hours SMOH. TBO 875 hours.
1975 – Started life an o-360-a4k.
1975 – 1987 – Converted to an a4m. No records are available on the history prior to 1987.
November 1987 – Overhauled and cam replaced.
June 1997 – Overhauled and cam replaced.
December 2002 – Repaired and cam replaced.
June 2005 – Overhauled.
April 2008 – Repaired due to cracked case.
Current condition
August 2012 – Filings evident in the engine oil and filter found during routine maintenance.
September 14, 2012 – 10 hour filter change. Filings still evident, oil sample sent for analysis. Oil sampling is of limited use however, as we have not been conducting routine analysis.
Oil leak from the crank case gasket has been ongoing and Bakerview are aware. This was to be corrected during the last routine maintenance service, due to the metal being found, it has been postponed until a decision on the engine is made.
The aircraft is now on a 10 hour maintenance inspection cycle. It must not be flown beyond the 10 hours from last filter inspection. Bakerview estimate we may not get more than another 20 hours of flight time before we have to address the engine issue and the aircraft will be unserviceable. This decision is still subject to the filter inspection results.
At present the aircraft is being flown very little.
Vendor Comments
From Bakerview Aviation:
‘As we had discussed the engine of C-GZHQ Lycoming O-360-A4M is making metal, steel, most likely from the camshaft and or lifters. This is an old style engine of flat lifter type. I am prepared to sign it out with a notice to inspect the engine oil filter within 10 hours. The options I have come up with are to remove the engine and have Progressive Air in Kamloops replace the cam and lifters. The options are new or reground camshaft and lifters.
The price to repair is $6100.00 for new and $5300.00 for reground cam and lifters and that is the fee for the engine shop.
There would be freight on top of that, I would guess $250.00 each way. The cost to re&re the engine would be $2500.00 labor.
The oil cooler would have to be flushed, due to metal contamination, $400.00. The engine time continues as is after the repair. The time now is 1125.5 hours. The recommended overhaul time is 2000 hours.’
From Chad Van Vliet Vantech Aviation Inc.
‘Engine repair, camshaft and lifters would subject to engine evaluation upon tear down. As a base line for repair, I would budget $8000 Cdn. Labour portion would be the same as replacement. While it would not be foolish to repair the engine, taking into account the long term objectives of the Abbotsford Flying Club, I would advise replacement rather then repair due to the open ended nature of the repair and lack of guaranteed longevity.’
Further to the GM on Wednesday, September 12, 2012. We investigated the option of having our engine rebuilt by Okanagan Aero. The result of this was:
From Chad Van Vliet, Vantech Aviation Inc
‘As follow on to our telephone conversation I conferred with Okanogan Aero Engines and confirmed that conversion of your engine to roller tappets is not possible during a field overhaul. That is the conversion can only be done at Lycoming.
His pricing for a field overhaul at his facility was approximately $4000 less then the factory remanufactured engine with roller tappets.’.
Options (All prices are plus HST, which the club can recover)
Option 1: Repair the defects. Cost $8-Timeline 3 – 4 weeks.
Pros
– Lower initial cash outlay.
– Shorter downtime than option 2 & 3.
Cons
– If further damage is found or problems occur prior to TBO, costs increase significantly.
– Has had 3 new cams, several overhauls and major damage repaired.
– After repair will still be the flat tappet design which has contributed to the problem.
– 37 year old engine
– Limited warranty, extending only to the parts replaced.
– Must use genuine Lycoming parts to be able to exchange the core in the future.If after taking the crank apart, further damage is found and it is decided to go for the factory rebuild after all, Lycoming charge a $3-6k penalty depending on the damage found.
Option 2: Overhaul existing engine. Budgeted cost max. $25k. Timeline 3-5 Weeks.
Pros
– Lower initial cash outlay than factory rebuild.
Cons
– Overhauled and major repairs on at least 5 previous occasions.
– 37 year old engine.
– History 10 years prior to 1987 unknown.
– This engine is old technology with flat tappets, which have reliability and wear issues.
– Warranty limited.
Option 3: Replace current engine with a Factory Rebuilt. The same engine as we recently installed inCost approx. $30k Timeline 5-7 Weeks.
Pros
– Zero time engine, 2000 Hours TBO.
– New roller tappets. This model was released in 2005.
– Two year warranty.
– Rebuilt to new engine tolerances.
Cons
– Higher initial cash outlay
– Core exchange penalty as the exchange is not like for like. (We have since managed to get Lycoming to waive the core penalty, so we can have the like for like price).
Cost Comparisons
Part of the club aeroplane rental rate includes a replacement recovery element (engine replacement reserve account), at $12 an hour. This is set aside to be used for future overhaul or replacement of the engine, but not repairs. Repairs do not come out of this account. With 1125 hours on the engine at $12 an hour cost recovery, we already have $13500 in the account to replace or overhaul the engine.
- 1.Repair the defects at $8-10k this is our minimumComes from maintenance account.
- 2.– $25k minus the $13500 in the engine reserve account . Net cost $11500.
- 3.Factory rebuilt $30k minus $13500 in the engine reserveNet cost $16500
Our minimum cost, which we would have to spend is $10k to repair the fault. In the engine reserve account we have $13500. Therefore we can allocate $23500 to an overhaul or replacement engine.
The real difference to consider when making this decision, which represents the lost 875 hours TBO:-
- 1.Repair existing problem $10k (estimate). This would buy us another 875 hours. The engine reserve account would continue to accumulate until we replace the engine in 875 hours (or sooner if other major faults occur).
- 2.current engine – $1150 This will take us to 2000 hours TBO
- 3.Factory Rebuild – $3000 This will take us to 2000 hours TBO
Conclusion
Repairing the existing engine is a lower cash outlay, but higher cost to the club. It has inherent risk of finding further problems and other issues occurring in the future. The engine has a sketchy history in its early life. It is 37 years old and has already had several overhauls and major repairs. This is very much an unknown and carries significant risk.
Overhauling, whilst the lower cost to the club, also carries risk due to the sketchy early history pre 1987, the age of the engine and having several major repairs and overhauls and being the old flat tappet technology.
Should we find more extensive or expensive damage during overhaul or repair, we run the risk of a $3-6k penalty should we later change our minds and want to go for the rebuild after dismantling the existing engine. We also are at risk of not being able to return the core at all once the crank case is opened.
A factory rebuilt engine has a slightly higher cost to the club, however taking into account the $13500 already recovered toward engine replacement and the $10k minimum cost (repair), this significantly lowers the real cost. The benefits of a factory rebuilt engine are significant to the club.
After investigation of the various options, the lowest risk and most cost effective option, taking into account the engine reserve account and for the long term, is to replace the existing engine with a factory rebuilt engine and return the core for credit to Lycoming. In addition while this is being done, we should also consider upgrades to the instrument panel as has been suggested by a number of members and the aircraft refurbishment committee. No budget has been set yet for the panel upgrade.
The current average usage of ZHQ SMOH is 160 hours a year. A factory rebuild replacement engine would potentially offer 12.5 years TBO. Although there is always a risk an engine could fail at any time, based on the history of our current engine, a factory rebuilt engine is significantly lower risk than a repair or overhauling our existing engine.
When using the Add Comments feature below, please put your full name in the Title field.