AW139 Nf (NR) control issue

[twinbird]

We operate two AW139 and I think one of them has a Nf (NR) control issue.
When it was picked to hover by a trainee with NR set to 102%, ROTOR HIGH came out and NR indication showed 104%.
I didn't think the control by my trainee wasn't bad though it was not exactly the same as the one by a pilot who has type rating.

And when we did RTO training by using TRNG MODE, when a trainee set CLTV down to recover NR right after activating TRNG MODE,
NF (NR) going up rapidly and NR HIGH came out. The control was not that fast, I think.

If somebody knows the same issue and knows how to troubleshooting, pls comment on it.

[the coyote]

Transient limit is 106% for up to 10 seconds. Did it exceed that? Sometimes it might take a second or three to sort itself out. In older non-digital and non-verbal aircraft, it most likely wouldn't have even been noticed.

[noooby]

What do your mechanics say?

[Sir Korsky]

It's not unusual to get into the 103-106 caution range very quickly if you throw the collective down with a tailwind and heavy.

[jeepys]

Trng mode

and don’t forget in trng mode you are not failing an engine but only the presentation changes so being too hasty on the collective can often give a nr brief high.

How does it compare to your other 139?

[twinbird]

Originally Posted by the coyote

Transient limit is 106% for up to 10 seconds. Did it exceed that? Sometimes it might take a second or three to sort itself out. In older non-digital and non-verbal aircraft, it most likely wouldn't have even been noticed.

Thanks for the reply, the coyote.

If there is no maintenance action it's OK if NR goes up into Transient limit, but we need maintenance actions.
Need a visual inspection at or above Nf 104% and below 105%.
Need a inspection of free wheel at or above Nf 105%.

Nf is within limittion, though it's in Transient lmit, but maintenance is needed. This is a problem.

[twinbird]

Originally Posted by jeepys

and don’t forget in trng mode you are not failing an engine but only the presentation changes so being too hasty on the collective can often give a nr brief high.

How does it compare to your other 139?

Thanks for you reply, jeepys.

I've experienced 6 AW139 regularly for the past 6 yrs and this bird is the only one.
I don't care high side of NR very much unless trainees use CLTV at a normal speed.

But this bird is not similar to others.
When pick to hover by using CLTV not that fast with NR set to 100%, NR sometimes shows 102%.
I don't think this is normal.

[twinbird]

Originally Posted by noooby

What do your mechanics say?

Mechanics say EEC seems to be OK as when depart by CAT A Part A, it needs HOV PI +23% in 2 sec, there is no problem to maintain NR at around 102%.
And if there is a problem with EEC, EEC DATA or EEC FAIL will be indicated.

[Captain Catastrophy]

LVDTs misbehaving?

[twinbird]

Originally Posted by Captain Catastrophy

LVDTs misbehaving?

Could be, thanks!

[Leonardo Ontano]

Maximum power on the main gear box

Hello
I’m a dummy of this world and I’m attending my second type training : the first one on AB 412 and right now AW139 at the training academy of Leonardo Helicopters...
Then before doing an easy question I’m sorry my knowledgeness! I got problem about the two turbine and the coupling on the mgb: according to the manual the mgb is able to load 2200 shp, and the two engine output powers are about 1600 shp in AEO. The sum of this two power is about 3200 shp and the limit of the mgb is about 2200 shp. I could think that not all the power reliable comes loaded on the mgb. Till this step for me it works but when I reach the readout of the MFD I see the coupling of the two turbine by % of torque...the coupling in torque is about 100%. This information on the PFD makes me to the think that in this Moment 3200 shp are going in the MGB. This situation is impossible because the mgb’s limit is about 2200... Anybody could help me to understand how it works?

[[email protected]]

Look at your OEI Tq limits and you will see that the engine is not producing maximum power at 100% Tq - it has another 60% available.

So at 100% twin Tq you are not exceeding the MRGB limit.

This is why the 139 has such good OEI performance.

[twinbird]

Leonardo Ontano,

The indication of AW139 is different from B412, as there is no mast TQ indication in AW139.
As for B412 100% is the max TQ and this is mast TQ and each engine produce 50% TQ.
50%+50%=100% mast TQ.

As for AW139 in AEO max TQ, except transient power, is110% TQ and this means each engine produce 110% TQ so total 220% TQ,
though there is no indication of mast TQ. This equals to 2,200SHP. This is the maximum TQ that MGB are able to load.
In OEI, alive engine can produce up to 160% TQ, except transient TQ, and this is within max load that MGB can load.

Hope this is what you're talking about.