Buying a J400, items to check?

[mch]

Hi all,

 

I'm in the process of buying a J400. The plane/engine have now logged about 200h and are 2 years old. I'll meet with the builder and the plane in about a month to have a look at the plane and do some flights.

 

Are there any areas I should look at for wear & tear specifically in a J400?

 

When we do test flights, are there any indications (e.g. oil temp during climb) which I can use as an indication for the engine's condition?

 

Thanks for you input,

 

Mike (1st post)

 

 

[Guest brentc]

Hi Mike and welcome.

 

I have a J400 that I built and I'll try and note a few things that I've found that might be of help. I'm considering selling mine so am using this as an exercise for myself to make sure things are all good.

 

Engine wise.

 

- The builder / operator should have (by the book) done compression or leakdown tests for the 100 hourlies. These are in the book so no excuses for those.

 

- Oil temp, on an average day you'd be hoping for no more than 90. If you did some circuits with steep climb at say 80 knots you should not see more than 90. If it was say 25-30 degrees+, then perhaps closer to 100 could be expected if it's being driven hard.

 

- Cylinder head, mine doesn't go over 250 usually. Not uncommon for them to sit on 300 or a bit more, but not into the red (or yellow if fitted)

 

- Engine should feel strong and hit approximately 2,800rpm statically

 

- Make sure that they are not running the lean burn kit. Fuel burn for a few jollies should not be less than 20-21 (with stopping and starting), whereas on a longer flight say an hour or two, perhaps 23-24.

 

- Prop should be smooth with very limited vibration if set up correctly. If there is a cam lock on the top of the cowl or a point you can reference you should be able to see this clearly and it should not look blurry in flight (don't worry if this doesn't make sense)

 

- Oil cooler, there have been updates to these since the originals on the 3300. The original is around 30cm by 15cm x 1.5cm deep and silver in colour. These are prone to failure. For longjevity it should be a black one. That being said there is no requirement for the owner to have fitted a new cooler at all.

 

- Pull off a rocker cover and check for metal deposits in the oil. I have see deposits in 80 hour engines

 

- They should have cut open the oil filter at each service to check for metal - believe me, it's not uncommon to find metal particularly due to premature rocker bush wearing

 

- Can't think of much else as 200 hours isn't many on the clock

 

Other items to check over:

 

- Make sure a good job was done of the wiring in the dash. If it was a factory assist this shouldn't be a problem. If it's a birds nest back there (like mine) it will take a while to fix.

 

- Brakes, the single calliper setup is worthless, it should have the dual calliper config. About $400'ish to upgrade. You might struggle to stop in under 500 metres with the single units

 

- If and when you do make the purchase make sure you have a reasonable number of hours flying it before you load passengers in the back. Performance goes from a sportscar to a mack truck with weight in the back. Usually with full fuel you'd be looking at 80 + 80 + 80 kilo's for your pax. Don't expect 4 persons. You can, but not full size adults and if you did have 4 you would almost most certainly have to ditch fuel.

 

If I think of anything else I'll let you know.

 

 

[mch]

Hi Brent,

 

thanks for the fast response!

 

Well, the electrical wiring is about the only thing I'm not afraid of, since I'm an electrical engineer .

 

However, my experience or knowledge about engines is about zero, so your advice in this regard is most welcome!

 

About the weight (4 full sized adults) this is not a problem for me. Unfortunately no problem: In my country I cannot fly the J400 legally with 3 or 4 persons anyway!

 

I would also expect a severe shift on CoG with a relatively light plane, much more so than with the C172 I'm flying now.

 

About the brakes I also agree, I must say that I even don't really like the 2 caliper ones. I know them and, well, to me the assembly looks a bit flimsy. But then the Jab is a light plane :) and my home strip has 900m tarmac.

 

Mike

 

 

[Guest brentc]

I operate out of 970 metres at sea level. At near 700 kg's with a strong crosswind with the old brakes on occasion I struggled to stop in that distance! The crosswind just keeps the aircraft sailing along down the runway.

 

The twin calipers work very well but could be better.

 

At 200 hours you should hopefully be fairly safe as it's not really enough time for much damage to have occurred unless it's been completely neglected.

 

I can put 130kg's in the back of mine with no major issue (2 x 80 in the front), but wouldn't like to put in much more than that.

 

 

[mch]

Well, I've heard about the floating capabilites of the J400-family but 970m is quite a way to go!

 

I'll have to practice a lot a I think to get used to it. The C172 flaps can produce an awful amount of drag when applied fully so you can really drop down fast.

 

Fortunately there are no obstacles in either direction of my strip and due to a ridge parallel to the RWY there is seldom significant crosswind.

 

So for practicising this is great until you feel safe enough to go elsewhere.

 

(Of course the wind funnelling ridge creates its own problems shortly after TO or when you turn into base as the wind direction may sometimes even change by 180 degrees while you are still/already slow and close to ground ...)

 

Back to the J400: I think I read in the POH 3 years ago that the maximum load for the back seats is 100kg. Has this changed or do you just fly it with 130kg in there occasionally?

 

The prospective seller has installed a (removable) additional 90l tank that goes onto the back seat. So he can go for 10h+ or at least he does not have to refuel for that time.

 

Since the J400 is reduced to a J200 for me (legally) this comes in quite handy for me.

 

Have not heard of that before I must admit.

 

Mike

 

 

[Guest brentc]

The amount you can carry in the back is wholely dependant on the C of G for the specific aircraft but 100 - 120 sounds right for most aircraft, but possibly more. Increased fuel load is behind the C of G so this would be relevant.

 

If you'll have 2 large people in the front and a bit of gear in the back (even with that tank too) you won't go wrong with C of G, just as long as you're within the a

 

appropriate weight range and stall speed for your country of registration.

 

I wasn't actually referring to the 'float' of the aircraft, but rather the way it 'sails' in a strong crosswind because of the large tail and small brakes.

 

 

[mch]

Ok, I did indeed misunderstand you. The idea of the verctical fin acting as a sail and the plane cruising like a sailboat is news to me :)