Post Landing Elevator Trim

[WisamH]

Hi Team,

Regarding the current behaviour of elevator trim after landing/rollout is that it will automatically set to a value that will enable based on THS. 

Based on observation IRL, the elevator trim should be set to neutral (I believe 4 degrees up).

Can this be looked into and whether this logic needs to be corrected.

Thanks,

Wisam

[IniJamir]

I will ask the team, thank you.

[IniJamir]

16 hours ago, WisamH said:

Hi Team,

Regarding the current behaviour of elevator trim after landing/rollout is that it will automatically set to a value that will enable based on THS. 

Based on observation IRL, the elevator trim should be set to neutral (I believe 4 degrees up).

Can this be looked into and whether this logic needs to be corrected.

Thanks,

Wisam

Are you able to get media of this happening in the mean time, if not I'll try to get around to it, thank you 🙂

[WisamH]

Hi @IniJamir,

Please find below video.

Once the aircraft vacates the runway you can see the trim going into the neutral position. Noting this is the same behaviour on both the -900 & -1000.

Thanks,

Wisam

[ool]

According to FCOM (-900 variant):

After landing, the pitch trim will move to 0,8° (maintenance position) when the speed goes below 30 kt.

The maximum THS deflection is between 0.8° and 13.7° nose up, so the correct after landing setting would be the lower end of the THS range (leading edge of the THS moves fully up). At the moment, the after landing setting on the Inibuilds aircraft seems to be 2.0° nose up, so there is something to be fixed there.

[IniJamir]

1 hour ago, WisamH said:

Hi @IniJamir,

Please find below video.

Once the aircraft vacates the runway you can see the trim going into the neutral position. Noting this is the same behaviour on both the -900 & -1000.

Thanks,

Wisam

My apologies I meant a video in the simulator

[IniJamir]

8 minutes ago, ool said:

According to FCOM (-900 variant):

After landing, the pitch trim will move to 0,8° (maintenance position) when the speed goes below 30 kt.

The maximum THS deflection is between 0.8° and 13.7° nose up, so the correct after landing setting would be the lower end of the THS range (leading edge of the THS moves fully up). At the moment, the after landing setting on the Inibuilds aircraft seems to be 2.0° nose up, so there is something to be fixed there.

Do you have that page of the FCOM so I can send it along to our team alongside media of the aircraft in sim, failing to do so, if not no worries, I just have to find time to grab it

[WisamH]

Hi @IniJamir,

Snippet below. After rolling out, the elevator trim is going to the optimal THS setting below the PFD not the neutral/maintenance position.

[ool]

12 hours ago, IniJamir said:

Do you have that page of the FCOM so I can send it along to our team alongside media of the aircraft in sim, failing to do so, if not no worries, I just have to find time to grab it

Regarding the FCOM, I'll send you a DM.

The pitch trim position can be observed from the F/CTL SD page. I checked again the functioning of the THS in the sim and I noticed the following issues:

• The THS range is incorrect, it is from 13,7° UP to 2,0° DN. It should be from 13,7° UP to 0,8° UP.
• THS moves to after landing position right after touch down, it should move below 30kts.
• The after landing position of the THS is incorrect, 2,0° UP. It should be 0,8° UP as described in the FCOM.
• The pitch trim indicator on the F/CTL SD page does not reach the bottom of the scale when the trim is in the lower end of the trim scale.
• THS is incorrectly animated in the outside view. When the THS is in the full UP position, 13,7° UP (that means aircraft nose up, not the THS itself), the leading edge of the THS should be fully down. And vice versa: when the THS is full DOWN position, 0,8° UP or "the maintenance position", the leading edge of the THS should be fully up and the indicator lines on the left side of the tail should be aligned. This movement to maintenance position can also be observed in the Cathay video above.
  
  1. This is pitch trim 13,7° UP and corresponding THS position in the outside view. This is how the outside view should look like when the THS is in the other end of the trim scale (0,8°UP). Also note the indicator lines aligned.
  
  
  2. This is pitch trim at 2,0°DN and the corresponding THS position in the outside view. Should be the other way around as stated above. Also note the pitch trim scale on the F/CTL SD page.
  
  
  3. This is the current after landing trim setting (should be 0,8°UP).