560 And 555 - Same Group?

[hungstart]

We recently started to operate a Bell 206.

The MM states that oil in the engine and xmsn must be of the same group as the freewheel can transfer oil. Engine O&M states that indescriminate mixing is not recommended. The machine we have runs 560 in the engine and 555 in the xmsn.

Are they of the same group? What is a group? Is there any Service Letters addressing this?

[skywrench1]

We recently started to operate a Bell 206.

The MM states that oil in the engine and xmsn must be of the same group as the freewheel can transfer oil. Engine O&M states that indescriminate mixing is not recommended. The machine we have runs 560 in the engine and 555 in the xmsn.

Are they of the same group? What is a group? Is there any Service Letters addressing this?

<{POST_SNAPBACK}>

 

These oils are not the same specification and are not interchangeable. Shell 560 is a third generation MIL-L-23699 oil with a high thermal stability intended primarily for use in engines (also approved in most drivetrain applications). Shell 555 (DOD-L-85734) is intended for high load applications that exist in drivetrains, its formulation is not condusive to high temperature applications, its resistance to coking is not great. While Bell maintained for years that the transmission and engine oils be the same spec due to the potential for oil transfer, this view has changed. For some time now the advantages of using application specific oil has outweighed any risk of oil transfer, as witnessed by their delivering a/c with 3rd gen oils in the engine and triple nickel in the drivetrain. I don't view the transfer issue as a big deal as it is easily detected and the duration of exposure to intermixed oil would be very unlikely to create a problem.

[hungstart]

Thanks skywrench

My thoughts are the same, although I did not know that bell was delivering a/c

in this configuration. I would think they would issue a little note stating this is accaptable.

[skywrench1]

Keep in mind you are talking about a JetRanger, where you can run 23699 in the drivetrain as well. For simplicity sakes, I would do just that as a jillion 206 drivetrains have been operated in this manner without difficulty. I would definitely recommend the 3rd generation oil for the engines due to their resistance to coking. While a 250 operated in a JetRanger isn't particularly taxed and isn't normally temperature limited, the benefits are still there, you won't likely ever see a leaking #5 carbon seal (smoking after shutdown) or carbon issues in the #6 & 7 bearing area. Another potential plus is Roll-Royce authorizes a 150 hour inspection interval if you run 3rd gen oils, scav oil filters and wet spline starter drives. Depending on your operation it can help spread out the scheduled maintenance and reduce costs a bit.

[hungstart]

I realize this is the way to go for the benefit of the xmsn and engine.

Is there any T.B. or CSL that addresses the issue of going against what the MM says regarding two different oils. What does the manual say for a 407 that

is delivered (I believe) with 560 & 555. If the manual says there are two different oils allowed than great, but in a 206, it makes a point of noting this fact in the engine servicing and xmsn servicing paragraphs. Everybody I talk to says this is the way to go. I just want some sort of approval.

[Blackmac]

You are not going to get approval here, that's what the manufacturer is for.

[hungstart]

I have been talking to Bell, they said to send an email or fax and I will recieve

something in writing in about a week. I wasn't looking for approval in this forum,

Blackmac, I was wondering if anyone participating in the forums knew of any manufactures documents containing the info I desire.