XL2 forward cog issue

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tafisama
Posts: 111
Joined: Wed Dec 18, 2019 9:09 pm
Based: Adelaide,SA
Tail Number: XLY
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XL2 forward cog issue

Post by tafisama »

I am not sure if this has been brought up before.I recently discovered that the XL2 has issues with cog going out of envelop with a higher weight in the seats even though the weight will be within limits.I could not go with an instructor who is over 200pounds,myself being around 170 pounds.The zero fuel weight cog was out of envelop and we agreed I had to go with lighter ones.We got limited to the amount of fuel we could carry as well.In the Manual, the XL2 must have some baggage in the rear to bring the cog back and that further limits the fuel to be carried.One experienced instructor said there is a piper model that has the same issue.With the XL,the cog lies behind the seats meaning a higher weight in the seats will push the cog way forward.The fuel is behind the cog limits meaning as fuel is burnt the cog shifts forward.
Has anyone else been in the same situation and what have you done to try and correct this?
We took a walk to one experienced engineer who laughed at the issue and said a little thinking was needed.Later he mentioned adding some ballast at a point way back.He said a small weight at the back will solve the issue.
I had to think of a perfect place to place some ballast and I got one.Placing a 1.5 or 2kg weight on top of the ELT solves the problem.It is easy to secure the ballast with the clamp or belt at that point.It is Station 163.You will not need any weight in the baggage and cog will always be within the envelop.It allows carrying more fuel even if you have 400pounds in the seats,the cog will be within the limits of 82.2-86.75(1650 model).

We have not done this yet because the engineer said there is some paperwork that needs to be done.I wish Liberty had realised this and issued some Work Instructions for the APs or Lames.
Last edited by tafisama on Wed Jun 15, 2022 10:55 am, edited 1 time in total.
N645XL
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Re: XL2 forward cog issue

Post by N645XL »

I can’t answer your question but you don’t say whether you’re aircraft has the gross weight mod. I think the unmodified aircraft already have (had) a 10 lbs ballast mounted in the tail.
Good luck.
tafisama
Posts: 111
Joined: Wed Dec 18, 2019 9:09 pm
Based: Adelaide,SA
Tail Number: XLY
Certificates Held: PPL

Re: XL2 forward cog issue

Post by tafisama »

Mine is 1650lbs.It might be that the 10lbs was not enough or they could not put more weight in the section,probably half a lb more could have solved it.I normally fly one up and full fuel with no issues but in this instance we needed to do some airwork.When I put in the weights I could not believe it,seeing how far forward the cog was at zero fuel weight.
GimpyPilot
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Re: XL2 forward cog issue

Post by GimpyPilot »

I (180 lb.) flew #81 with the higher gross-weight kit, along with a 210 lb. instructor, at half tank, within CG. As I recall, it was close to the edge of the envelope, but remained within limits all the way to zero fuel. Handling characteristics were not adversely effected. As noted, there is a 10(?) lb. ballast in the tail that is removed when installing the high gross weight kit.
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BRADLOUTH
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Re: XL2 forward cog issue

Post by BRADLOUTH »

Yes I took a friend up that weighed 250 pounds....took fuel down to 10 gallons and put 40 pounds of weight in back of cargo bay to balance. We were heavy but plane flew OK for a short sight seeing flight...OK COG

best...b
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