Arrow IV W&B CG Too Forward
Join Date: Aug 2002
Location: Norway
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Did a skill test in another brand multi engine many years ago. 3 candidates same examiner. All planned a trip including W/B. No problems for the other but i was unable to load within limits. The other two plus several earlier candidates with same examiner used sample data from AFM. Plane grounded for investigation. Found out there was two procedures for weighing either on wheels or jacks. Weighted on one calculated on the other.
I worked at a school with a 150 Aerobat, with a 172 engine, which had the same problem. As we were spinning it - it was a serious problem.
In thge end I asked the engineer if he sould move the aircraft battery further aft in the tail to correct the problem -that's one solution.
In the end the school installed a 150 engine, though....
In thge end I asked the engineer if he sould move the aircraft battery further aft in the tail to correct the problem -that's one solution.
In the end the school installed a 150 engine, though....
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As we were spinning it - it was a serious problem
What was the problem ? On the surface, I think you are suggesting that the bird had a too-forward CG. This should make recovery easier ?
What was the problem ? On the surface, I think you are suggesting that the bird had a too-forward CG. This should make recovery easier ?
Join Date: Apr 2024
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Hello PPRuners...
I'm getting concerned with a situation with a weight and balance calculation of a Piper Arrow IV.
The CG limits are 85 to 93 inches, and starting from 2400lbs up to 2900lbs, the forward limit gets closer to the aft limit, with MTOW having 89 to 93 in of buffer.
The aircraft in question has a BOW of 1808lbs since its last weight and cg determination, and the CG was at 79.96 inches.
I found it strange that the BOW of the aircraft had the CG so off the envelope, since the chart just went back to 81.8 in. The envelope starts at 85, but the cg is off the charts!
Still, I redid several times with different calculations as to how the aircraft is normally operated (full tank, half tanks, 3 POB, 2 POB, no baggage, etc.)
Everytime the CG is off limits, too forward.
Now, the common conception (what I think is a misconception) around here, is a culture where people disregard doing W&B for small aircraft, that is inaccurate, etc. etc. etc., and that a few inches off the envelope doesn't do harm, you just rotate with a little higher airspeed and such...
My question is, is it 3 or 4 inches forward of the cg limit (if the forward limit is 85 inches, I'm talking here 81, 82 inches) not to worry about? Is it not that a bigger deal?
Or are we seeing here a future accident?
What worries me more is that, with fuel burn the CG moves further forward, so in landings it's gonna mean trouble. People constantly tell me that the roundout to touchdown the aircraft has a heavier nose and it's hard to pull, to trim up, etc. But that does seem normal with some aircraft.
Should I worry about this or not?
All inputs are appreciated.
If a CG more forward than the certificated limit is acceptable and the aircraft has been flying for a long time without any incident, how does one measure the actual true value of the CG limits of light aircraft's AFM/POH?
How do you convince the pilots and operatores of this small aircraft to respect the manual and the W&B procedures, when they always operate out of the envelope and nothing dangerous ever happens?
Thank you in advance!
I'm getting concerned with a situation with a weight and balance calculation of a Piper Arrow IV.
The CG limits are 85 to 93 inches, and starting from 2400lbs up to 2900lbs, the forward limit gets closer to the aft limit, with MTOW having 89 to 93 in of buffer.
The aircraft in question has a BOW of 1808lbs since its last weight and cg determination, and the CG was at 79.96 inches.
I found it strange that the BOW of the aircraft had the CG so off the envelope, since the chart just went back to 81.8 in. The envelope starts at 85, but the cg is off the charts!
Still, I redid several times with different calculations as to how the aircraft is normally operated (full tank, half tanks, 3 POB, 2 POB, no baggage, etc.)
Everytime the CG is off limits, too forward.
Now, the common conception (what I think is a misconception) around here, is a culture where people disregard doing W&B for small aircraft, that is inaccurate, etc. etc. etc., and that a few inches off the envelope doesn't do harm, you just rotate with a little higher airspeed and such...
My question is, is it 3 or 4 inches forward of the cg limit (if the forward limit is 85 inches, I'm talking here 81, 82 inches) not to worry about? Is it not that a bigger deal?
Or are we seeing here a future accident?
What worries me more is that, with fuel burn the CG moves further forward, so in landings it's gonna mean trouble. People constantly tell me that the roundout to touchdown the aircraft has a heavier nose and it's hard to pull, to trim up, etc. But that does seem normal with some aircraft.
Should I worry about this or not?
All inputs are appreciated.
If a CG more forward than the certificated limit is acceptable and the aircraft has been flying for a long time without any incident, how does one measure the actual true value of the CG limits of light aircraft's AFM/POH?
How do you convince the pilots and operatores of this small aircraft to respect the manual and the W&B procedures, when they always operate out of the envelope and nothing dangerous ever happens?
Thank you in advance!
Moderator
One important consideration relates to what the empty W&B actual data is.
Without boring you with this and that, suffice it to say that, if the starting weight and CG is not reasonably accurate, all bets are off regardless of how you might go about calculating the loaded weight and CG. If things don't appear to be right, and you can't figure out a sensible reason when checking the sums .... the first port of call is a reweigh to rezero the base data ....
Without boring you with this and that, suffice it to say that, if the starting weight and CG is not reasonably accurate, all bets are off regardless of how you might go about calculating the loaded weight and CG. If things don't appear to be right, and you can't figure out a sensible reason when checking the sums .... the first port of call is a reweigh to rezero the base data ....
Blessings everyone. I just saw this chat and joined. a little about me. A&P IA own Avio Fix Pro LLC, GA aircraft Maintenance. I just installed a Factory new Continental Engine on this Piper Turbo Arrow IV and went from a 2 blade propeller to a 3 blade Simitar McCauley. all flies well but the owner that has been flying the aircraft for over 30 years stated that the performance is awesome but has to pull back on the yoke more as you guys stated and it caught my attention the forward cg scenario, the new engine is definitely beefier and 3 blade propeller is heavier. definitely a forward cg situations. i will perform a weight and balance but if so nose heavy. do I add ballast in the baggage compartment. your input is totally appreciated. thank you Gents.
Back in the day, 1990, I did a lot of my CPL training in a T tail Arrow. Many solo navs and it was a turd to land, ran out of elevator when the tail stopped flying before the wing. There were 4 of us using 2 of the aircraft and after a few W&B exercises we actually put 2 x 20Kg sandbags in the luggage locker. Instant fix.
