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Furthest Traveled in a 150/152

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Furthest Traveled in a 150/152

Old 8th Jun 2013, 22:00
  #41 (permalink)  
 
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Que? The weight schedule is three years old.

Where did I say I was looking at the original weight schedule?

Last edited by thing; 8th Jun 2013 at 22:06.
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Old 9th Jun 2013, 00:45
  #42 (permalink)  
 
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Thing

So the fact that your airplane is so much lighter than every other C 152 in existence doesn't concern you at all ?
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Old 9th Jun 2013, 01:51
  #43 (permalink)  
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A weight loss program for an older aircraft is entirely possible....modern goodies are so much lighter than the original fit... Add in a strip an respray to remove the collected paint layers and you can easily end up lighter than delivered from the factory... Not a LOT lighter normally, but enough to make a real difference.
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Old 9th Jun 2013, 01:54
  #44 (permalink)  
 
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What "goodies" can you change on a C 152 that will reduce the weight 70 lbs ?
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Old 9th Jun 2013, 06:36
  #45 (permalink)  
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Once had an aircraft professionally weighed by two different people, there was 150 lbs difference. Decided that the lighter figure was correct
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Old 9th Jun 2013, 08:57
  #46 (permalink)  
 
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So the fact that your airplane is so much lighter than every other C 152 in existence doesn't concern you at all ?
There has to be a 152 somewhere that is the lightest, maybe this is it. I have a feeling that even if I took it to the shop of your choice and they weighed it ten times you still wouldn't accept it. Also let's say you were right, how come I can fly it at MTOW and it operates in a perfectly acceptable way? No sluggishness getting off the ground, 100kt cruise at 2,400?

Four other weight schedules from the same place:

PA28-161 Warrior 2, weight schedule 1532 lbs. Does that sound about right or is that 100 or so lbs too light?

Exactly the same model as above, weight schedule 1448 lbs. Crikey it must be a mistake, how can it weigh less than the one above? Ah, it doesn't have a DME and other goodies.

C172 with standard tanks and 160hp engine, weight schedule 1483 lbs.

C172 with long range tanks and 180hp engine, weight schedule 1545 lbs.

Do they sound about right or are they all underweight too?

Last edited by thing; 9th Jun 2013 at 08:58.
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Old 9th Jun 2013, 10:24
  #47 (permalink)  
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Can't see the weight schedule being wrong
I will objectively state that weight and balance records for GA aircraft are for my personal experience (and in this case, that lots) the most screwed up and untrustworthy documents I encounter in my work.

My Transport Canada advisers have many times told me to pay extra attention to this, as they have been made aware that not every Cessna was actually weighed before leaving the factory. Some had optimistic weight and balance documents prepared based upon similarity.

When I am doing approval work for which the W&B is critical, I witness the weighing. My experience has been to see it done right first time about 20% of the time. It would not have been redone had I not squawked. Imagine my client's surprise in my insisting that I travel from Toronto to Vancouver to witness a weighing, to find that indeed, it was more than 150 pounds optimistic in its first attempt.

I ask the shops who weigh aircraft for the approvals I do the weigh them three times, changing the scales under the wheels each time. You'd be amazed at the surprised looks on their faces when they have trouble getting within 1% each of the three times, and we end up weighing even more times to actually determine the weight.

Be suspicious in the extreme if an aircraft has a W&B which seems optimistically light, or less than factory or previous weights. It is very rare for aircraft to get lighter with age, unless lots of equipment is removed, and not at all replaced. The weight of a full IFR suite of avionics is rarely more than 15 pounds in a GA aircraft, and there's not much else which gets removed and replaced.

Remember that if the weight is not correct, and C of G position probably is not either, and that could affect the aircraft handling even more dramatically than a wrong weight.
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Old 9th Jun 2013, 10:37
  #48 (permalink)  
 
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Ah, thanks for that DAR. If weight schedules are in general incorrect though would having them reweighed make any difference? In that the error margin is likely to be just as great on the reweigh?

Does this also mean that most of us are flying in a/c that are not correctly within w/b?

I must admit, as I've said before that the a/c flies perfectly normally at what I think is MTOW according to the weight schedule. (I've flown other 152's of the same age and fit and can compare).

How much 'fudge factor' does the a/c manufacturer build into the w/b graphs? Obviously if youre a pound overweight or the loaded moment is slightly out then the a/c isn't going to come crashing out of the sky.

Edit: I was always led to believe that DME equipment in particular is quite heavy. I'm talking about 70's stuff now not modern kit.

Last edited by thing; 9th Jun 2013 at 10:42.
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Old 9th Jun 2013, 11:10
  #49 (permalink)  
 
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Where did you say you were reading the original weight schedule?

The empty weight in the POH, you know the official Cessna handbook that the people at Cessna wrote is 1101 lbs. Ours has had some avionic changes that have reduced the weight to 1080.3 lbs. I've even taken some photos of the relevant pages/documents but I've a feeling even putting those up will make no difference
As Cessna obviously did not weight your aircraft 3 years ago then.......

So you should now suspect that either your airframe has been fitted with a helium flooding system, or the W&B might be a tad optimistic! Certainly the one I had a share in weighed more than 1250lb. But then it did have a Nav/com AND DME
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Old 9th Jun 2013, 11:42
  #50 (permalink)  
 
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My fault, that was quoting the Cessna empty weight (the generic empty in the POH) as opposed to the weight schedule weight, which is the one everyone is at odds with.

The whole thing is a concern for everyone really, if as DAR says weight schedules are in general not that good. Either that or we can all breath a sigh of relief that our a/c can operate well outside of the envelope.

Last edited by thing; 9th Jun 2013 at 11:44.
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Old 9th Jun 2013, 11:44
  #51 (permalink)  
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How much 'fudge factor' does the a/c manufacturer build into the w/b graphs? Obviously if youre a pound overweight or the loaded moment is slightly out then the a/c isn't going to come crashing out of the sky.
Very true. There is a fudge factor built in to W&B, and it is described in the FAA flight test guide. When flight tests are done for certification, aircraft are flown slightly overweight, and slightly outside limits. But they are also being flown by a pilot who is extra skilled in flying safely through an unexpected event.

Saying that the plane flies "normally" in the configuration you're flying it might be overlooking a few details in the dusty corners, which might very suddenly become vitally important. Structural capacity, stall speed and performance are all affected by the gross weight. Add weight, surrender some of each of the three - how much are you willing to surrender?

Stall and spin recovery characteristics are affected by the C of G location. "Normally" in normal flying might be okay, but if the unexpected happens, the plane might not recover in the same why you've come to expect. I have flown a Cessna 206 in which at a certain, very attainable configuration, full elevator down control input would not lower the nose - that's scary bad, and C of G dependent. The aircraft was not misloaded - believe me, I triple checked!

When you pilot an aircraft, you're always thinking ahead, looking for the unsafe condition which you would rather carefully avoid than have to skillfully deal with. You're looking for the bad weather which could be ahead, the ATC clearance which might put you in conflict with another aircraft, the destination which might have too great a crosswind. Would it not seem odd, in that aura of caution and self preservation to blindly accept as accurate a W&B which seems too good to be true?

It is probable that the W&B records for the aircraft right back to the Cessna original are with the aircraft, or easily available. Sit on a rainy day, and go through them, doing all the additions and subtractions, and see if they pass the sanity check. As I have said, the empty W&B is the MOST screwed up things I encounter with aircraft - 'cause it is one of the more difficult things for the pilot to quickly recheck!
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Old 9th Jun 2013, 11:51
  #52 (permalink)  
 
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I agree, but we can't check the w/b and have to go on what it says on the bit of paper. That being the case, and bearing in mind that pilots of vast experience who have been in flying, both military and civil all of their professional lives fly the same a/c and haven't flagged it up, how is a relative sprog like me supposed to pick it up, and how often is it happening at airfields all over the world and in all types of a/c?

It's quite a cause for concern surely?
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Old 9th Jun 2013, 16:22
  #53 (permalink)  
 
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Thing

My advice and it is worth every penny you paid is to go to your club manager and say that you are concerned that that the weight of this aircraft seems unusually low compared to every other similar aircraft and that you think it should be reweighed.

If the answer is no then I would use the Cessna Sample empty weight, 1238lbs in my flight planning. Low powered light aircraft like the C 152 will be disproportionately effected by flying overweight and so care should be taken not to allow the already meager performance margins to be reduced.
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Old 9th Jun 2013, 18:31
  #54 (permalink)  
 
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Already had that conversation BPF thanks. It has been questioned and reweighed which is why the last weight schedule was done, with the figures that it has. I'm assured that its been looked into as apparently the question of it's weight (or lack of) was a cause for concern.

Just back from shooting instrument approaches in it actually, two up, tanks full no probs.

I think it's just one of those weird ones, maybe it's made out of balsa...

By the way, where do you get your sample weight from?

Last edited by thing; 9th Jun 2013 at 18:32.
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Old 9th Jun 2013, 19:48
  #55 (permalink)  
 
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Originally Posted by thing View Post

By the way, where do you get your sample weight from?
Page 6-9 of the official Cessna POH for a 1979 C 152. You guys do have a Cessna issued serial number specific POH I hope ?
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Old 9th Jun 2013, 21:37
  #56 (permalink)  
 
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Of course. I don't have it to hand but I'll have a look at it next time I'm at the club and quote the weight.
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Old 10th Jun 2013, 10:39
  #57 (permalink)  
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You guys do have a Cessna issued serial number specific POH I hope ?
I would be very surprised to see a serial number specific Flight Manual for a C152, I don't recall ever seeing one, I think they were generic back then for the small Cessnas. Any weights quoted in the Flight Manual would be generic in any case.

However, what is relevant, and could be expected to be with the aircraft would be the original Cessna factory weight and balance. It's usually in a wad of weight and balance documents stuffed in a pocket somewhere. A rainy day review of that document, and the subsequent W&B revisions can produce surprising information. Do they pass the sanity test one to the next? Would it appear that what was changed from one revision to the next justifies the change in weight stated?

That's where I see mistakes, typos and transposition errors much too often....
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Old 10th Jun 2013, 15:02
  #58 (permalink)  
 
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Originally Posted by Pilot DAR View Post
I would be very surprised to see a serial number specific Flight Manual for a C152, I don't recall ever seeing one, I think they were generic back then for the small Cessnas. Any weights quoted in the Flight Manual would be generic in any case.

However, what is relevant, and could be expected to be with the aircraft would be the original Cessna factory weight and balance. It's usually in a wad of weight and balance documents stuffed in a pocket somewhere. A rainy day review of that document, and the subsequent W&B revisions can produce surprising information. Do they pass the sanity test one to the next? Would it appear that what was changed from one revision to the next justifies the change in weight stated?

That's where I see mistakes, typos and transposition errors much too often....
Prior to 1976 officially there was no such thing as a POH. All that was required was the appropriate limitation placarded in the cockpit. However all manufacturers issued what was in effect an owners manual.

In 1976 however as a result of a GAMA initiative virtually all of the manufacturers adopted a standard format POH which then became a required document. When ordering a POH from the manufacturer you have to provide the serial number of the aircraft it is for and the front page of these will have a space to record the serial number.

Since all C 152's were built in 1978 or later it will have a proper POH. For C 150's however only the last 2 years of production, 1976/1977, have a proper POH. I used to teach at a school that had 2 1976 C 150M's.

Last edited by Big Pistons Forever; 10th Jun 2013 at 15:04.
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Old 10th Jun 2013, 17:33
  #59 (permalink)  
 
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I did 3 hours 11mins in a C152 once.

Most. Uncomfortable. Flight. Ever.
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Old 10th Jun 2013, 21:17
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Had a sneaky peak at my Mrs's log book. Sandtoft to Toussus le Noble in a 152 with the long range tanks. March 1993, 3.9 hours. Next day Toussus to Challes 3.3.
On the return trip Montellimar to Caen 4.5
Now I know why her butt is the shape it is!!!!
One important thing about the 150 is the low fuel consumption. You get a lot of mileage if the rear end can take the pain, years of horse riding is obviously a benefit.
Weighing 8 stone also helps.

Last edited by ericferret; 12th Jun 2013 at 08:37.
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