Engine Rebuild

 

This article describes an IO-540-C4D5D engine rebuild, to comply with SB569.

 

Background

During the period 1997-2002 Lycoming's crankshaft subcontractor produced around 6,000 crankshafts using a modified forging process. This would probably not have been a problem in itself but both Lycoming and the subcontractor also had sloppy quality control practices and, around 2001/2002, somehow managed to make some batches of crankshafts which were structurally weakened. Some of these snapped in flight with loss of life in some cases; some broke within hours from new. This fiasco resulted in the FAA issuing an AD (Airworthiness Directive) recalling many crankshafts by serial number - presumably those made with the defective procedures were identifiable by batch. By the end of 2005 there were no more recalls but litigation in the USA dragged on, both between aircraft owners and Lycoming, and between Lycoming and its crankshaft subcontractor. This class action (local copy) is worth a read for some background, though it doesn't seem to have got anywhere.

Eventually, on 11th April 2006, Lycoming issued a Service Bulletin SB569A (local copy) which placed a 21 February 2009 life limit on these crankshafts, additionally mandating its replacement if the engine crankcase is opened up for any other reason.

This SB led to various national CAAs issuing an Airworthiness Directive, making the crankshaft change mandatory. However the AD may be more relaxed in the deadline than the original SB. For example, the FAA AD 2006-20-09 (local copy) allows a 12 year deadline starting when the crankshaft entered service. This 12 year limit means that all the affected crankshafts must be replaced between approximately 2009 and 2014.

However, it is up to each national CAA how to construct the AD from the SB. The Turkish CAA, for example, has taken it literally, grounding all affected engines on 21 February 2009.

Lycoming paid for engine removal/replacement and all the work on the early recalls but they are not paying for the cost of SB569A; they are saying that there is nothing actually wrong with these remaining 5,000 or so crankshafts and indeed none of them appear to have yet failed.

Lycoming have done two things to reduce the compliance cost:

a) owners can purchase a new crankshaft for US$2,000 (this includes new bearings and piston rings and is a fraction of the normal crankshaft cost) though this offer expires February 2009;

b) owners sending their engine for an overhaul to Lycoming will get a new crackshaft fitted free.

The latter is a "clever" move which may well protect Lycoming from a class action, because they have always adopted a position that an engine must be overhauled after 12 years anyway. The upshot of all this is that owners who are rightly suspicious of Lycoming's quality control procedures, and who would have used an independent engine rebuilder instead, have until Feb 2009 to change their crankshaft. The Feb 2009 deadline is particularly cynical because it forces those who do not trust Lycoming to do it before the 12 year deadline; presumably the objective was to spread out the replacement crankshaft demand while ensuring that those who are unable to choose an earlier date are forced to use Lycoming's factory overhaul service regardless of what they think of it.

Given that most private owners do any major maintenance in the winter (due to weather) the $2000 offer left three possible winters: 06/07, 07/08 and 08/09. The last one is probably not a wise choice since owners using independent engine shops are likely to do it then, and owners happy to send their engine to Lycoming will probably do it at the last minute i.e. at the 12 year deadline which will be 2009-2014 depending on when their engine was made.

I decided to do it in the winter of 07/08.

 

Objective

The objective comprised of compliance with the SB569A crankshaft replacement requirement, and improving the engine by a higher grade reassembly process than is done by the manufacturer.

 

Which Engine Shop?

One has to do some "due diligence" before sending an engine off to an engine shop.

Most consumer surveys, whether published or anecdotal, of aircraft or engine maintenance organisations find that for every happy customer there is at least one unhappy one. The least bad problems are delivery times that massively over-run previous estimates, in some cases forcing the retrieval of the disassembled engine after 4-5 months and transferring it to another engine shop to finish it. Then it gets worse, with serious build defects causing engine failures. Outright document forgery to cover up work which was not actually done is not unknown. The worst horror stories often come from work done by the best known companies. One can speculate on the reasons for this variation; it could be that "aviation has always been like that" but the most likely reason is that many customers want to pay peanuts which strips the businesses of the capability to employ good people and run proper project estimation and management systems. In general, car mechanics are paid a lot more than aircraft maintenance people. There is also the tight regulatory environment of aviation maintenance which enables a firm turning out poor work to hide behind its approvals and certification - businessmen familiar with ISO9000 will recognise this immediately - and this is exasberated by the European approach to certification which is to apply it to the organisation rather than to an appropriately qualified individual inside the organisation which is how it's done in the USA.

The next requirement was to eliminate downtime if possible. Traditionally this is done by getting an exchange engine. Unfortunately, whereas my engine had only about 700 hours on it, most engines in the exchange marketplace are much older; around 5,000 hours. Because the value of an engine (and thus the aircraft) relates to how old it is, most owners overhaul their own engine when it's young and use the exchange option only when it is old. A 5,000-hour engine should be fine because all parts of relevance are either replaced or tested for cracks, but the methods used cannot detect a subsurface crack (particularly in aluminium) and there are other factors e.g. a crankcase which has been through a couple of overhauls will have had its mating surfaces machined down to a level where it will have to be replaced the next time - very expensive! It would be foolish to swap a 700 hour engine with a known perfect history for a 5000 hour engine with a totally unverifiable history and potentially any number of undeclared prop strikes. Finally, my particular IO-540 engine variant, an IO-540-C4D5D (dual magneto single shaft) is rare and is thus very rare in the exchange engine marketplace. I could have done an exchange by buying a new engine but at around US$60,000 (minus what one can get for the old one after paying for the SB569 crankshaft swap on it) this is an expensive option, especially as many careful buyers then send the engine to a specialist engine shop to be "looked at" in case Lycoming forgot to tighten up some screws inside it...

The final requirement was to get back an engine reassembled to the closest possible tolerances, particularly with respect to dynamic balancing of moving parts. Lycoming assemble engines with relatively wide tolerances on component weights and dynamic balance limits, which results in some engines being much smoother than others. This is accepted as normal in aviation but should not be. Specialist engine shop practice in the USA is that pistons and gudgeon pins should be weight matched to within 1g (1 gram), con-rods are weighed separately at each end and also matched to within 1g, and the crankshaft is dynamically balanced to within 1 gram-inch. What a mix of metric and imperial units! On crankshafts, Lycoming's factory tolerance appears to be around 50 gram-inches. Yet, it is difficult to find a UK engine shop which is interested in dynamic balancing of a crankshaft and many won't do even trivial measures like weight matching the pistons - something a child could do with £20 postage scales.

 

Is "Blueprinting" Legal?

"Blueprinting" is an old expression which in this case means building the engine from carefully weight-matched parts, and "gas flowing" by smoothing out the inlet manifold passages to aid airflow into the engine.

Dynamic balancing of crankshafts is completely legal under FAA rules if done by an FAA Repair Station with the appropriate authorisation for this scope of work. I have not found anything suggesting it is illegal under CAA/EASA rules either although some UK engine shops claim otherwise (but never offer references to back up the claim). It is controversial as - if done properly - it involves removing metal. What most critics don't realise is that the manufacturer already does dynamic balancing and removes vast amounts of metal when doing it, using a rough grinding process which would not look out of place on a building site. Incomprehensibly, the manufacturer then stops without bothering to finish the job accurately.

Weight matching of reciprocating parts obviously cannot be illegal since good or bad weight matching is entirely accidental in normal engine assembly so doing it more accurately deliberately is no different. If however one is to remove metal then the company needs the appropriate FAA authorisation for the scope of work. One does not generally need to remove metal from pistons because they are cheap and plentiful and selecting a weight-matched set is easy, but if metal does need to be removed there are well established locations on the base of the piston. One would not remove metal from Lycoming con-rods as these have no "fat" but again it is easy enough to find matched sets especially as one can match an underweight small-end with an overweight piston.

Gas flowing is routinely done on engines operated under the U.S. Experimental regime and is very effective in increasing engine efficiency (power for a given fuel flow rate) by reducing pumping losses. Regarding certified engines, my enquiries suggest that most FAA inspectors would approve the removal of casting flaws in the inlet passages, but anything beyond that is a no-no. And a certified engine is not permitted to exceed its maximum factory rated HP anyway so any result would be limited to a reduced fuel consumption - yet the fuel servo needs to be adjusted to a specific full throttle flow rate band so, perversely, that would make a significant efficiency gain illegal too.

Finally, there is a variety of certified aftermarket parts which can potentially be fitted. After many discussions with engine shops I avoided these as most offer very little benefit but for example one can get a camshaft which contains additional oil feed holes; this assists lubrication during engine starting but with modern oils and frequent flying is not an issue. The one thing which would have been worth getting is the new Lycoming roller tappets (cam followers) which avoid a well known Lycoming issue with tappet surface disintegration, but these require new crankcases which are very expensive.

 

UK Engine Builders

Advantages of a UK engine shop include: avoidance of shipping cost, delays and damage - the engine goes in the back of a van; the bigger shops are EASA certified so no future issue with aircraft registry transfers; one can drop in and sort out any problems face to face.

One engine shop offered to rebuild the engine with weight-matched parts, but they would achieve partial crankshaft balancing merely by matching an overweight crackshaft big-end bearing with a con-rod whose big-end was similarly underweight; no dynamic balancing of the crankshaft itself. This firm was not EASA145 approved, but that doesn't really matter. This firm looked good initially but further enquiries revealed a dodgy engine work history of some of the people involved.

Another UK engine shop, this time a well known and EASA145 approved one, offered to rebuild the engine with a dynamically balanced crankshaft (sourced from Lycoming, then passing through a specialist U.S. crankshaft balancing shop which charges around $200) for which they would generate an EASA-1 form for £800 over the crankshaft price - a markup of 7x for the EASA paperwork. This was amusing though irrelevant on the scale of this project but ultimately I did not use that company due to too many reports from unhappy customers who used this firm in volume.

Another very well known company (which went bust soon afterwards) claimed that parts sourced from the USA come with bogus documentation... At this point I had enough.

There are definitely some small engine builders scattered around the UK who do excellent work. Unfortunately they are not easy to find references for, and some of the reports I have seen were terrible. A common thread seems to be timescales which are totally out of control, with some highly reputed builders taking 4 months; OK if one is doing an exchange engine, or one is working a bigger project on which the engine is not the critical path. Most of the very small shops don't have EASA approvals which restricts the use of the engine to a Private CofA G-reg (not a problem for a private aircraft). For an N-reg aircraft one needs an FAA A&P (A&P/IA if it's a geared engine) to sign it off.

 

US Engine Builders

My aircraft is on the U.S. (N) register so I have no need for EASA documentation, but there is always the simmering issue of an attack by the European regulators on foreign registered aircraft in Europe. Some notes on the acceptance of U.S. paperwork to CAA/EASA when placing an aircraft onto the G register are here.

In the USA, there are many specialist engine shops which have FAA Repair Station approval for dynamic balancing using metal removal. Compared to the vast amounts of metal already removed by the crankshaft manufacturer, the amount removed in this secondary process is small and there is no safety issue in this very long established practice. The metal is also removed in the same locations at which the manufacturer removes it. The FAA Repair Station then issues the finished engine with an 8130-3 form. But you don't get an EASA-1 form - that can come only from the biggest "production line" engine overhaulers and none of those look good in U.S. consumer satisfaction surveys.

You can however get an 8130-4 form - an Export Certificate of Airworthiness - by paying another ~ $300 to cover the cost of the engine shop calling in an FAA DAR (Designated Airworthiness Representative) to sign the certificate. With such a form, the engine is good for any EASA aircraft except perhaps AOC operations (this situation is unclear at present).

I contacted a number of U.S. engine shops, starting with the big well known ones. A recurring issue in dealing with companies in the USA is that they have the world's largest market on their doorstep, don't need to deal with foreign customers, don't need to deal with any customers who ask more than three questions, and this is reflected in frequent difficulties in communications. The company's work may be good but if they don't answer emails or faxes prior to doing business, one would be a fool to send them one's engine. I also used a survey done by Aviation Consumer (an excellent non-advertising subscription-only U.S. aviation publication) to eliminate a number of names. This was followed by informal enquiries among U.S. pilots.

 

Barrett Precision

After examining the options for several months during the latter part of 2007, I settled on Barrett Precision in Tulsa, Oklahoma. I found a number of satisfied former customers, zero unhappy customers, and they communicated in a straight and open manner. They offered a wide range of options on the extent of work done in this case: the crankshaft swap is an engine "repair", not an "overhaul".

Their pricing was good too: $3600 for the most basic option which included dynamic crankshaft balancing and weight matching of reciprocating masses, all to 1g, and with cylinder work starting at $150/cylinder it would have been hard to reach the prices quoted in the UK which started around the $15,000 area and those assume that no new parts are needed. They had apparently previously dealt with UK customers and the cost of air freight was estimated at only $500 (each way) using Eagle Global (now called CEVA) who they had used previously.

A full overhaul costs much more - $32,000 - because it includes e.g. new Lycoming cylinders and many new parts. If my engine had e.g. 1500 hours, an overhaul might be worth doing but not at 700 hours. Interestingly the TB21 engine, a TIO-540, would cost $48,000. These are still highly competitive prices by UK standards.

A 1 hour dyno run is included as standard, with extra time beyond this charged at $500 per hour. I specified 5 hours total engine run time - more than most owners go for but this should bed in the piston rings, making the first flight less critical.

Barrett Precision offer a warranty of 2 years or 400hrs, whichever occurs earlier. In the USA, the engine would generally be sent back to them. Here in Europe, they would ask the customer to nominate a known-reputable engine shop and would liase with the shop regarding rectification work. However the majority of issues tend to be cylinder related, do not require the crankcase to be opened, and can thus be done by any reasonable maintenance shop. Obviously one is not expecting trouble - if one was then one would use a local UK engine shop where one can give them a hard time if necessary.

Barrett Precision's dyno run includes a lean test, where they check that the six EGTs peak at the same common fuel flow rate. My engine was originally fitted with a set of GAMI injectors (these are standard Lycoming injectors, with flow rates selected to match airflow imbalances between cylinders in order to balance up the cylinder power delivery) and it is important that the engine work does not upset this selection. A new set of GAMIs costs about $1000.

They confidently quoted a 5 week turn-around.

Barrett Precision are located in an area containing numerous aviation engineering companies. They can get parts and engine accesory overhauls, cylinder machining, etc, done virtually on their doorstep.

 

Shipping the Engine

The new crankshaft was ordered from Lycoming some weeks before the engine was shipped. I had heard some scare stories (from UK engine shops) about long delivery times on crankshafts and thus my original intention was to not send off the engine until the crankshaft had arrived; Barrett advised that the crankshaft was due around mid-Dec 2007. Unfortunately there was a mix-up somewhere on the delivery time, the crankshaft did not turn up, and my own enquiries with Lycoming found it was scheduled for mid-Jan 2008. I was going on holiday in late December and do not have access to the hangar over Xmas, so I decided to ship the engine off mid-Dec as I would not have been flying anyway.

The engine was packed using a method recommended by Barrett, involving a standard 47" x 41" pallet with a sturdy 47" x 41" x 36" high cardboard box sitting on top of it. The engine is drained of all fluids, wrapped in a polythene sheet, and lowered into the carton with a crane, leaving several inches' gap underneath. The void is filled with commonly available two-pack expanding foam; I purchased it from here (Foamseal 200). A quantity of used tyres were placed in the corners of the carton so less foam was needed - the pack purchased claims to do 0.5 cubic metre which was somewhat optimistic. Finally, the carton is strapped to the pallet with some tape. The pallet must carry appropriate "treated timber" markings otherwise the whole shipment will be rejected upon entry to the USA.

I had asked Barrett to ship the specially-marked pallet and the carton to me, which they did using their engine shipping company Eagle Global Logistics (now called CEVA). Unfortunately the CEVA delivery man discarded the pallet upon delivery, making this the most expensive delivery ever of a cardboard box, at about £200! A phone call to CEVA UK revealed that these pallets are dead common and cost about £10 and they delivered another one.

This is where the problems started. CEVA sat on the engine package for two weeks, claiming afterwards that the export invoices were missing. These, I was originally advised, were to have been generated by CEVA who were collecting the package for Barrett and who were paid by Barrett. Typically of many shipping companies CEVA made minimal attempt to contact me about this and 2 weeks later I discovered it was still sitting at Heathrow! Finally, it was delivered to Tulsa but it sat there for two more weeks because a lazy CEVA employee was (on her own admission) too busy to process the U.S. Customs paperwork. 4 weeks, for a transit which should normally take 4 days!

The disaster was alleviated to some extent by another disaster: much of Oklahoma suffered a severe snowstorm over Xmas which cut the power to a huge area, so Barrett would not have been able to do much on the engine anyway. At the same time, the UK was having one of the worst winters for flying...

 

The Engine Rebuild

I visited Barrett Precision in mid-Feb and some of the following is based on my visit.

Barrett dynamically balanced the new crankshaft when it arrived. It was 15 gram-inches out when it arrived from Lycoming; they brought this down to 0.7.

The following pic shows some of the areas (A,B) where Lycoming remove metal (a lot of it; 5-10mm in thickness) to dynamically balance it, to 15 gram-inches

The following pic shows additional suprisingly rough machining by Lycoming

The original crankshaft is nitrided - this is a surface hardening process which yields a hard-wearing surface while preserving a tough core. The additional machining done by Barrett Precision is done in similar areas to A/B; less than 0.010" of metal is removed and if more needs to be removed the crankshaft is re-nitrided.

When the engine was stripped down, the biggest suprise was a fair amount of corrosion inside the cylinders

This was below the level of the top piston ring so was not affecting compression. It's a mystery how it got there since I fly once a week, for never less than 1 hour, and the longest the engine ever went without flying was about 3 weeks. This is a high level of usage for a private pilot and if this is not enough to prevent engine corrosion, what is? Also the aircraft is always hangared. On the basis of this usage, Barrett believe that the corrosion was most likely there before the aircraft was delivered, but this leads to another mystery: the engine had a shock load inspection (prop strike during taxi) when just a few hours old; this was done by a well known UK engine shop who could not have possibly missed this corrosion - assuming that they actually opened up the engine and not merely resprayed the outside... Unfortunately enquiries within the UK maintenance business suggest that the latter possibility cannot be ruled out.

Some cylinders were a lot better, with the corrosion only just visible

Fortunately, the corrosion was not as bad as it looked. It was smooth to touch and not deep enough to require a rebore; it came out with a standard re-hone which should always be done anyway whenever piston rings are changed.

The combustion area was fine in all cylinders

and most importantly none of the cylinders had the most feared and very common aircraft engine problem: cracks.

The only other notable items were the tappets (cam followers)

showing spalling (breaking up) of the tappet surface. This is a well known issue with Lycoming who even refer to it here (local copy) (page 25) blaming it solely on the use of reground camshafts and tappets. The real reason is widely believed to be defective metal or heat treatment. These tappets are not expensive and were replaced.

Suprisingly, the camshaft - a common problem location in early-2000s IO540 engines - was clean and had very little wear.

It was reground to new factory limits. Barrett Precision rebuild the engine to new factory limits, not overhaul limits which are looser. This is a bonus over what one normally gets in an overhaul from elsewhere but it does mean some parts are discarded when they could have been re-used in an legally "overhauled" engine.

The rest of the engine was in good condition - very clean and confirming that 700 hours of lean-of-peak (LOP) operation is just fine.

The exhaust valves were about 0.002" undersize on the stems - this is within overhaul limits but outside new limits - and were replaced; a significant item at $200 each. The exhaust valve stem is filled with sodium which becomes liquid at about +97C and helps to transfer heat away from the valve face. The following pic shows both the exhaust valve and the larger inlet valve. Inlet valves rarely show much wear as they run much cooler.

The conrods were fine - nothing to wear on them as the bearings are separate - and were re-used after NDT (nondestructive test using a magnetic field method to check for cracks). The conrod bolts were replaced with new - this is mandatory.

Most engine shops, Lycoming included, assemble the engine and spray over the whole thing, covering all the bolts and other fittings. Barrett paint the major engine parts (cylinders, crankcases) separately and install the fittings (screws etc) afterwards. The original fittings were largely re-used after re-plating

and this results in a much cleaner looking engine.

There are various options on engine colour, from the Lycoming grey through various "look what I've got" options such as the following

which are more attractive than the standard Lycoming grey, but here in Europe would be a "red rag to a bull" to any inspector looking at the aircraft at a later date who would immediately assume the engine belonged to a cowboy who filled it with speed mods from an American hot rod shop. So I reluctantly went for the grey.

The cylinders are painted on the steel sections but left bare on the aluminium sectionsm for best heat transfer to the air

The engine is reassembled by one person on a bench, and then goes into a dyno room (the pic below is another, turbocharged, engine)

with instrumentation in an adjacent room

The dyno run turned up a problem with the fuel servo: the fuel control valve was not closing properly, causing a shudder at shutdown. This suprised me, as the shudder had always been present, and is usual with these engines. However, according to Barrett, this is not how it should be.

 

The Finished Engine

Around 10 weeks after it was delivered to Barrett Precision, the engine came back.

To avoid another disaster with CEVA, I sought the help of some colleagues in the USA (it's usually much cheaper to book UK-USA or USA-UK shipping from the USA end) and one of them had a good contact at Fedex who delivered the engine back to the UK with great speed - in about 3 days door to door. I did try to get Barrett Precision to get some quotes in the USA from the usual courier firms but they were too busy.

Barrett Precision require payment in full at the very end, before shipping. This was done by a bank transfer which arrived, suprisingly, the same day.

As expected, it was very well packed using the polyurethane expanding foam method

Initially it appeared that taking the foam apart would make a huge mess but in fact it was packed between two sheets of plastic which created two foam "caps"; one under and one above the engine, and these two halves opened up easily.

It looked good too

The only reservation was a cosmetic one: the aluminium pushrod shrouds were unpainted and are likely to corrode fast. Unfortunately removing them for a paint is a big job which involves removing the rocker covers and gear and draining the tappets and would take all day, so I decided to simply coat them with some clear protective spray.

One of the pushrod shrouds was bent, which is a mystery given the very good packaging of the engine. Fortunately they cost only £15, but the labour cost is significant.

A dyno report was included which showed that the engine delivered 231HP which after correcting for nonstandard pressure and temperature comes to 246HP. The actual fuel flow rate was 23 USG/hr. This is close to the 250HP book performance at standard atmosphere (ISA) conditions. 246HP is very good for an engine with new bores and pistons which is still tight. The dyno report also shows the lean check on the GAMI injectors.

A couple of things were forgotten at the Barrett end in the final days before shipment. The 5 hour dyno run was done for just 1 hour which is their standard procedure; I wasn't bothered about this because they cannot do it continuously at 100% or even 75% due to insufficient cooling air, and at $500/hour the cost is a lot more than flying the whole aircraft. The 8130-4 form (the Export CofA) never happened; this doesn't matter as the engine is being fitted to an N-reg aircraft but not having the 8130-4 would be a total disaster if fitting to a G-reg (the engine may have to go back to the USA for a re-inspection).

 

The Cost

The basic engine repair came to $11600. This includes the $2000 Lycoming exchange crankshaft kit and $2400 on new exhaust valves and tappets. The remainder is mostly small parts and labour.

By any measure, this is a very competitive price. However, the freight both ways and import duty and VAT have the potential to add a lot on top.

The eventual invoice from CEVA was $625 for the UK-USA air freight which is very good value and would be great if they did not take 4 weeks! They did produce what appeared to be a quote of $1400 for the engine return - a blatent ripoff for the same journey and on the same scale as some of the couriers would have quoted for the same (225kg) package. However, with CEVA it was not possible to work out whether this was real or a mistake.

The import duty and VAT are yet to be worked out. It is very important that the outbound documentation describes the engine as going to the USA for a repair and it will be returned to the UK. Similarly on the way back to the UK otherwise import duty on the whole engine value will be charged.

 

Project Management

On this project, three things went wrong on timing: the new crankshaft, the outward shipping, and the engine repair itself. Clearly there are lessons to be learnt.

Firstly, the specially treated pallet is widely available for about £10. What is not available off the shelf is the correct size carton for the engine. One could get Barrett Precision to ship one of these (flat packed) by any conventional means but it is quite large and this is likely to cost at least £100 using for example DHL. For £100 one can probably get any packaging company to make a stack of such cartons out of standard triple-wall card... Do not ask Barrett to ship this carton by air freight!

The crankshaft delivery time turned out to be within days of the date quoted to me by Lycoming's distributor (Omaha). After the crankshaft has been ordered, anybody can phone up the distributor with the crankshaft S/N and check when it is due to be shipped. So, I should have waited until the crankshaft arrived at Barrett Precision and had been dynamically balanced. Then I should have waited until Barrett Precision had a time slot available to actually work on the engine. Only then should I have shipped the engine.

What to do about idiotic shipping companies is a difficult problem. I have 30 years' shipping experience from my business. Air freight is not an area attracting good people, and many firms (particularly the cheaper ones) are badly disorganised. The most popular "workload minimisation tactic" seems to be: something is not right on the documentation, so you make one phone call to the sender and if the line is busy or he is out, you chuck the whole wad of paperwork (with a post-it sticker saying "unable to contact") into a tray where it rots until somebody raises hell. No effort is made to contact the sender by other fairly obvious means e.g. fax or email, or perhaps trying to phone a few more times. In extreme cases the shipper might even charge storage costs and these can be substantial. So, one must phone the shipper every day to check progress and make sure nothing is "stuck". Obviously there is little point in speaking to the same monkey who is sitting on the documents so one needs to be ready to escalate an initially polite telephone enquiry to "The Management" if not getting a satisfactory answer. The reality is that most air freight shipments are completed within 1 week, but some get stuck and this is why one needs to keep on top of the job.

The express parcel companies (DHL, Fedex, etc) are generally much better and are set up to deal efficiently with the most complicated part of the shipping process (the documentation, and getting the package through Customs) but are very expensive, and some do not handle large items like an engine weighing 250kg. The best express quote was from TNT at £700 but they subcontract the job to .. guess who ... CEVA! They turn out to be the same company. DHL UK quoted me £1600 ($3200) each way and this is probably at the top end of the scale.

Finally, one needs to make it clear to the company collecting or delivering the engine that they need to come with a vehicle which has a forklift in the back of it - unless you have a forklift available locally.

A common occurrence with engine work is that some accessory gaskets are missing; when you purchase e.g. a new fuel pump then unless you request it to be installed, it will come in its box and without a gasket. It therefore pays to buy all gaskets just in case there is a problem. In this case we ended up a couple of gaskets short but engine parts are commonly stocked and usually easy to get.

This rebuild took around double the original 5 week estimate, but they had what must have been considerable backlog of work due to the storm over Xmas. Currently, Barrett Precision estimate a reasonable turnaround time at 8-9 weeks. It would appear that the best approach is for the customer to pre-book a slot with Barrett, and arrange his own shipping (even if this can be much more expensive if booked from the UK end). Try the usual express companies first; you may get a suprise especially if e.g. your employer is their major customer. The best quotes will however be obtained via a contact in the USA...

If fitting to a G-reg aircraft, make absolutely sure you get the 8130-4 (Export CofA) form which needs to be generated and signed by an FAA DAR who has inspected the engine at the engine shop prior to shipment. To avoid any possibility of it being missed out, I would suggest obtaining a faxed copy of this form before making the payment.

 

Did it work?

The engine was reinstalled in the aircraft, prepared as per the instructions provided, and started. Initially there were some problems: the bottom spark plugs kept filling up with a thick oily material, and had to be removed twice for cleaning. Eventually, a longer run was done, including a full power test and that cleared everything out.

During the brief full power ground run, it was noticed that the engine runs much smoother than before. Also, it shuts down with much less "shudder", confirming that there was indeed something wrong with the fuel servo.

During the initial 2 hour flight test it was immediately apparent that the engine is much smoother than previously. The difference is most noticeable at full power but is very present throughout the operating regime. Previously, the engine was OK at 2200rpm, rough at 2300, smoothest at 2400, and rough at the max value of 2575. All this has disappeared; there is no apparent good or bad RPM anymore.

There was however a noticeable rumble at 1200rpm (the ground idle speed)... but I knew this is not the end of the story since another variable was a newly overhauled propeller which had not yet been dynamically balanced.

Suprisingly for a new engine which should still be "tight", the aircraft performance exceeds the previous. The verified IAS has increased from 138kt to 141kt under identical conditions (economy cruise at around 60% power) which is probably equivalent to an extra 5% on the HP. Interestingly, the 138kt figure was consistent throughout the previous 6 years so there is something definitely "better" about the new engine.

The engine is for all intents and purposes a brand new engine and needs to be run in as per the Lycoming recommendations (local copy). In short, this involves running for a number of hours at a high cruise power setting of 75%, occasionally dropping to 65%, and this needs to continue until the oil consumption has stabilised. This process ensures the piston rings get properly seated into the bores without the bores suffering from being glazed over by burnt oil which results in an engine which has a high oil consumption. I found the oil consumption initially very high (around 1 quart per hour) with the expected spark plug fouling issues, but after about 30 hours it gradually reduced to 1/10 of that. I also found three small oil leaks at the flexible pipes feeding oil to the rocker covers.

Update 8/2009: An issue was gradually noticed whereby the #3 cylinder was running hotter, on both EGT and CHT, than the others. An examination of EDM700 data going back to 2002 showed that #3 tended to dominate on EGT (and in any case the absolute EGT value is not important, being affected strongly by depth of the probe insertion, etc) but not on CHT. A GAMI flight test was done, where the EGT and CHT values are logged against the common fuel flow and then plotted on a graph. This showed four cylinders being well in line but #3 and to a lesser extent #4 running a lot richer. This could not be a blocked injector which would have the opposite effect... After some work spent checking correct valve lift, etc, it was discovered that all the GAMI-supplied injectors had been installed in the wrong cylinders! Sorting them out sorted the temperature issue and a subsequent GAMI flight test confirmed that the temperature profile was back to its original 2003 value after the GAMI injectors were originally installed. I never found out for sure who mis-installed the injectors but clearly this is something to check when your engine comes back. It is however true that #3 has always had the highest CHT on my particular engine, and I think it is because of a gap next to it through which air can escape.

 

Dynamic Propeller Balancing

The 3 blade Hartzell prop was overhauled (6 year point) while the engine was away. This was done by a highly experienced A&P/IA/ATP/CFII man who I know personally and who is also an occassional pilot of the aircraft and he did the best possible job on it, including the most careful possible static balance.

From previous dynamic prop balancing sessions, I knew that the backplate and the spinner (which are obviously not included in the static balance of a prop) were significant contributors to previous out of balance issues, and I wanted to get rid of the rumble at 1200rpm. So I went off for this, my third, dynamic balance, at the excellent Worldwide Aviation at Bournemouth (EGHH). The first two sessions were 1. when the aircraft was brand new and 2. after a new prop was fitted following a pothole prop strike shortly after brand new (both in 2002).

The out of balance state of the two brand new props, fresh from Hartzell in 2002, were both around 1.5 IPS (inches per second). This is regarded as bad enough to ground an aircraft and indeed I did not accept the aircraft in the original delivery condition, due to the very obvious vibration.

The newly overhauled prop, statically balanced with the most extreme care, turned out at 0.65 IPS. This was twice as good as the two new props from Hartzell had been but was not good enough.

The prop was balanced with weights attached in the appropriate balancing locations on the hub, and is now balanced to about 0.06IPS. The 1200rpm problem is totally gone and it's smooth all the way up.

The moral of this story is that no matter how carefully you balance a prop statically, dynamic balancing can yield a very noticeable improvement. Or, that the contributions from any assymetry in the spinner and backplate are significant enough to matter.

The cost was about £250.

 

 

Update 5/2010: The FAA no longer exports engines and propellers with an Export CofA. The UK CAA now accepts these items with an 8130-3. The CAA leaflet is here (local copy). This makes it a lot easier to get engines and props from the USA. What happens in other destination countries, I don't know.

Update 9/2012: The FAA has issued a new AD which introduces some new serial numbers that are affected. The owners of these engines are well screwed, since Lyco's $2k crank offer has long expired.

Update 1/2013: A question arose when the 12 year AD deadline starts. I telephoned Lycoming and they said it starts with when the engine entered service which they regard as the date it was installed in the airframe. This should be the first entry in the engine logbook. Some aircraft owners, notably some trying to sell their aircraft, have been claiming that it starts when the aircraft CofA was issued (which in some cases gives considerable extra time; as much as a year perhaps) but I have seen no support from this position.

 

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This page last edited 26th January 2013.