Confused with MTOW

[Nev25]

Ive read that MTOW includes the weight of the Pilot and fuel

 

If this is correct and MTOW is 614KG for a 2 seater under 95 .55

 

If I was to buy say a J160 with a MTOW of 540KGs I would have to weight less than 74KGs to get it registered under 95.55

 

Or have I got it completely wrong (I hope so)

 

 

[Doug Evans]

Yes that correct mtow include pilot & passenger & fuel gear .

 

 

[shu77]

Depends if you mean MTOW as part of the aircraft design or within the context of RA registration. The later is something of an arbitrary number designed to keep RA pilots from flying anything too heavy in the RA category. It was previously 540kg and was increased in recent years to 600kg. You have the challenge with some types in that while they may be capable of flying at 600kg they were certified at 540kg and so now that is the weight available. You also have the consideration that the previous average weight for a pilot when calculating these things was 74kg (have a look at an old elevator placard it will suggest a load of say 1000kg but 16people!) Now I know I'm taking up more than my fair share of the 1000kg in that scenario and it was the same for planes.

 

The number used for calculations was changed to 90kg in the last couple years, so when the tech manager certifies a new type hes looking for empty weight + 2 hours fuel + 180Kg for a 2 seater rather than empty weight+2 hours fuel +150Kg. I recently saw the number 750Kg proposed as an MTOW that would provide a lot more interesting types.

 

There is much talk about the impracticality of imposing a MTOW for aircraft that might be quite capable of flying above them comfortably, the best argument I saw for this number was that it makes it impossible to register a Cessna 152 on the RA Register (given they are all quite old, there was a feeling placing them into a lower maintenance category like RA might not be a good idea) To a lesser extent too much weight can upset your centre of gravity, and provides extra wear on the undercarriage on a heavy landing, however personally I think we should lean towards having an empty weight and move away from having to keep the aircraft below 600kg and focus more on whether its balanced. I can't say for certain but Im fairly sure Ive seen a case on the tarmac of a J170 perform well when it was loaded over MTOW for example (not to imply the guy flying was fat....).

 

This is at least the understanding I have devloped over the last couple years lurking about this site, I am sure there will be people with more knowledgeable understandings that can correct me where I am mistaken.

 

EDIT: Opening statement was a little vague in terms of what I was referring to.

 

 

[Gentreau]

You have to have a declared MTOW for an aircraft, otherwise at what weight would you test it's structural integrity, stalling speed, manoeuvering speed etc etc ??

 

If an aircraft has a MTOW of 540kg, that's because it has been tested at that mass, go beyond it and you do not know how it will behave.

 

To answer the original question, if you buy an aircraft with a MTOW of 540kg, it doesn't matter what you register it as, it still is limited to 540kg.

 

.

 

 

[Riley]

MTOW for any RAA aircraft is the maximum permissable 'all up weight' of that specific aircraft as stated in it's certificate of registration, NOT the general MTOW limit set by CASA for that particular category of aircraft. For example, a early Lightwing GR912 can be registered under CAO 95-25 or CAO 95 -55 (both categories have an upper weight limit of 540kgs) but actually may be limited to 480kgs MTOW whilst later models of basically the same airframe/engine are certified to 540kgs. If in any doubt, check with RAA Tech Mgr.

 

 

[FlyingVizsla]

Here is a précis of weight in aviation:

 

EMPTY weight - the aircraft unloaded

 

GROSS weight - the aircraft loaded (people, fuel, luggage)

 

MTOW - what the Certificate of Airworthiness says is the maximum GROSS weight (above) that the aircraft can take off with.

 

MTOW is also constrained by the RAA & CASA regulations. For example if the RAA category says MTOW = 544kg (CAO 101.28), then the RAA registered aircraft is limited to 544kg, even though the CofA says 750kg which the VH registered aircraft can fly at.

 

MTOW is also recalculated downwards when conditions dictate - eg rough weather, high airstrip, hot temperatures, etc.

 

Maximum Landing Weight - can be different to MTOW ie you may be able to take off weighing 500kg but only land at 450kg (an issue if you are only doing circuits or short hops).

 

So - a good exercise for any pilot - read the Pilot's Operating Handbook for the aircraft and the Certificate of Airworthiness for the Weight data. Work out the weight of fuel, oil. Weigh the gear - first aid box, water, fire extinguisher, tie downs, maps, ERSA, etc. Now add pilot, pax, luggage and calculate how much fuel you can carry.

 

See the VFR Guide (you can download from CASA http://casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_90008 )

 

Also see CAR235 & CAO 101.28 (when CommLaw comes back on line - presently down for maintenance)

 

RAA Technical manual on RAA website

 

Sue

 

 

[crashley]

Max take off weight for raa is either 544 kg or600kg. This weight of airplane plus fuel carried plus pilot and passengers and all luggage. So if you we're ready to take off and you weighed the whole lot you must be under 540 or600 kg. a 160 c weighs 300kg empty so you have 244 kg for fuel pilot passenger and luggage

 

 

[Sapphire]

A plane can be at MTOW without the pilot. In that case the plane will never fly unless it's radio controlled or you can find a pilot weighing no more than 0 kg.

 

 

[Mriya]

From the answers given so far, I guess NEV25 is still wondering exactly what to think. So lets try to pull it all together...

 

As Gentraeu states correctly MTOW is the limit to which the aircraft was tested during certification (All up weight including everything), taking into account the structural integrity and aerodynamic capabilities of the design. Exceeding MTOW is venturing into a dangerous (and illegal) realm as the aircraft has not been tested or certified for operations above this weight. Each aircraft will have a MTOW which may or may not match the various weight limits imposed by the regulator (ie CASA / RAAus in our case) for particular categories of aircraft. For example there are plenty of RAAus aircraft with a MTOW well below the RAAus category limit. If the aircraft has a MTOW of 450kg, then this is its weight limit, regardless of the fact that RAAus aircraft weights are capped at 600kg (lets not complicate the description with waterborne differences). This means that for many aircraft, when you do the weight sums, once you carry a passenger it is likely that you will need to restrict your fuel uplift / cargo in order to stay under the aircraft MTOW.

 

As mentioned above RAAus has a 'category' weight limit of 600kg. This figure aligns with the LSA category rules, which is why when many designers build an aircraft they pick 600kg as their MTOW. If however an aircraft designer used a higher MTOW (lets say 750kg), for the aircraft to be registered RAAus, the category weight limit is the limiting factor. So in this case for the aircraft to operate legally under RAAus, it would not be allowed to be loaded above 600kg regardless of the fact that the aircraft has been tested to a higher figure. At one stage a couple of C152's /RV7's slipped into RAAus, with restrictions limting them to 1 POB and fuel uplift restrictions, which kept their TOW below the RAAus weight limits (544/600kg). In recent times it has been recognised that allowing aircraft like these on to the RAAus register was not 'in the spirit' of the regulations, and so now unless an aircraft clearly fits into the 600kg weight limit, including pax & reasonable fuel, RAAus will no longer allow these types to join their register (result is that C152's / RV7's / etc, stay VH registered now).

 

Hope this all paints a picture regarding MTOW & RAAus weight limits and how they are derived.

 

In short a RAAus registered aircraft must be operated at or below aircraft MTOW or the RAAus category weight limit, WHICHEVER IS THE LOWER FIGURE.

 

 

[Mriya]

Ive read that MTOW includes the weight of the Pilot and fuelIf this is correct and MTOW is 614KG for a 2 seater under 95 .55

 

If I was to buy say a J160 with a MTOW of 540KGs I would have to weight less than 74KGs to get it registered under 95.55

 

Or have I got it completely wrong (I hope so)

I've just re-read your original Q and realise I meant to address a couple of mistakes in your original assumption...

 

If a J160 has a MTOW of 540kg, this means that the empty weight of the aircraft will be significantly less. Here are some J160 figures from a quick google search

 

Empty Weight 649 lbs (295 kg)

 

Useable Load 539 lbs (245kg)

 

Gross Weight (MTOW) 1188 lbs (540 kg)

 

So in this case the aircraft weighs 295kg and has a useful load of 245kg. Useful load includes pilot, pax, payload & fuel. The sum of these two figures equals MTOW. The 614kg figure you quote has no relevance and I'm not sure where this figure came from.

 

 

[FlyingVizsla]

Nev is alluding to CAO 101.28, AIRWORTHINESS CERTIFICATION REQUIREMENTS — AMATEUR-BUILT CATEGORY AEROPLANES

 

1.1

 

 

(3) that has a maximum take-off weight not greater than:

 

(a) in the case of an aeroplane other than a seaplane — 544 kg; or

 

(b) in the case of a seaplane with a single seat — 579 kg; or

 

© in the case of a seaplane with 2 seats — 614 kg; and

 

His assumption is the J160 540kg MTOW is the empty weight and the pilot's weight is in addition, up to the CAO max 614kg.

 

Example - 614kg (max) minus 540kg (Jab weight) = 74kg max pilot weight allowed

 

This isn't correct. If the J160 = 540kg MTOW, that weight won't go up to the maximum for registration (544kg).

 

A correct example - the CofA says MTOW = 540kg. The empty weight = 295kg. Add the load - Pilot 110kg, pax 75kg, luggage 20kg, gear 10kg, oil & fuel 50kg = 560kg OOPS! Have to leave something at home.... On a lighter note this did happen and the guy said to me, we'll take the 20 litres in the jerry can ....

 

Sue

 

 

[boingk]

Ive read that MTOW includes the weight of the Pilot and fuelIf this is correct and MTOW is 614KG for a 2 seater under 95 .55

 

If I was to buy say a J160 with a MTOW of 540KGs I would have to weight less than 74KGs to get it registered under 95.55

 

Or have I got it completely wrong (I hope so)

Another example, this time using my aircraft, a Gardan Minicab 55 register craft.

 

Airframe weight: 314kg

 

Max Takeoff: 515kg

 

Useful load is 201kg, I call it an even 200kg for operational purposes. The category weight is 544kg but my airframe is limited to 515kg MTOW because of its design limits and cannot go higher than that.

 

Load up the 314kg aircraft with an 80kg pilot, 80kg passenger, 30kg fuel (about 40 litres) and 10kg luggage... and you're 1kg under your maximum takeoff of 515kg.

 

I like to think in terms of useful load - what load can a craft carry? Mine takes 200kg, other take more, others take less. I believe the good old Volksplanes are only designed with about 80~90kg useful load... wouldn't want to be a large person!

 

- boingk

 

 

[Guest Andys@coffs]

So probably the last piece of info that Nev25 is left wondering about is, where does this empty weight come from......

 

So the manufacturer of an aircraft will usually provide an empty weight in their sale brochures or online marketing gumph. Gumph is the correct terminology because it will usually be a kilo or some lighter than the lightest aircraft of any that they have delivered and probably requires the interior to be full of helium...... The weight that really matters is the empty weight that is specified in the Pilot Operators Handbook (POH) which is in the cockpit of every RAAus Aircraft. In that handbook will be the results that were obtained at the completion of the build process for that specific aircraft when the aircraft was put on the scales and weighed. The exact Kilos will be a function of how careful the builder was at managing weight from day 1 of the build process and what the fit out was in terms of avionics and other optional fit equipment.....

 

My Jabiru 230 is limited by RAAus to an MTOW of 600kg's but if the aircraft was built under VH experimental within GA then it can be MTOW = 700kgs (and instead of being the station wagon version can also have the rear 2 seats fitted..... That said I think the usual rule of thumb for seats in GA world is whatever the specification is, 2 of them to work, will need to hold young kids.... 4 adults in a J230 would not be my definition of fun, the only benefit is that the fuel load limitations are likely to mean that you wont be in back for long assuming a proper W&B config against rear seat real weight even allows it!

 

Andy

 

 

[Mriya]

Nev is alluding to CAO 101.28, AIRWORTHINESS CERTIFICATION REQUIREMENTS — AMATEUR-BUILT CATEGORY AEROPLANES1.1

(3) that has a maximum take-off weight not greater than:

 

(a) in the case of an aeroplane other than a seaplane — 544 kg; or

 

(b) in the case of a seaplane with a single seat — 579 kg; or

 

© in the case of a seaplane with 2 seats — 614 kg; and

 

His assumption is the J160 540kg MTOW is the empty weight and the pilot's weight is in addition, up to the CAO max 614kg.

 

Example - 614kg (max) minus 540kg (Jab weight) = 74kg max pilot weight allowed

 

This isn't correct. If the J160 = 540kg MTOW, that weight won't go up to the maximum for registration (544kg).

 

A correct example - the CofA says MTOW = 540kg. The empty weight = 295kg. Add the load - Pilot 110kg, pax 75kg, luggage 20kg, gear 10kg, oil & fuel 50kg = 560kg OOPS! Have to leave something at home.... On a lighter note this did happen and the guy said to me, we'll take the 20 litres in the jerry can ....

 

Sue

Thanks for that, I knew 614kg was not a figure that would apply to NEV's situation, but had not looked up the regs to find where the figure had come from. I did allude to the fact that waterborne aircraft have their own set of weight limits, but didn't want to go there as it would just complicate my attempt at describing the basics of MTOW.

 

 

[Yenn]

When I built my Corby there was no requirement to have a MTOW placard in the cockpit. The weights are recorded in the POH also balance info.

 

Now I have to put a notice saying what MTOW is. Don't ask me why, because it doesn't tell me how much fuel, pilot and passenger or luggage weight I can put on board.

 

To make the current labelling relevant we need all airstrips to have scales available before every flight. What nonsense. To fly an aircraft you need to read the POH and work out yourself what you can lift. Not have a useless placard.

 

 

[boingk]

Exactly, well said!

 

I find it amusing that my old Gardan has to have a placard and apparently an emergency procedures page in the POH. Pretty sure that emergency procedures are a thing taught in training, right? Oh gee I'm stalling... Where's the POH? Yeah, right!

 

I think a more appropriate placard would read Usable Weight, not Maximum. As it is I just bought an embossing label maker and made the simple placard myself.

 

 

[ave8rr]

Exactly, well said!I think a more appropriate placard would read Usable Weight, not Maximum. As it is I just bought an embossing label maker and made the simple placard myself.

I have to agree with boingk. ALL RAAus aircraft should display the max payload available or display the aircraft empty weight and MTOW. The aircraft empty weight and MTOW should also be quoted for all aircraft being advertised on the "members Market". This would give prospective purchasers an idea of what they can carry. I have asked sellers in the past the aircraft empty weight and been given the manufacturers design empty weight what good is that in determining a payload?

 

 

[Geoff13]

I am going through the same process atm. Looking at buying and the first email I have to send out is can you please tell me the MTOW and the empty weight. 90% of responses just quote manufacturers standards. I can get them off goggle. I am new to this and I want to buy something that I can fly legally with some fuel in it. There are not a lot out there that actually fit that criteria for 2 reasonably sized adults. I am not surprised at the thread that hints at some people being afraid of ramp checks..

 

Cheers Geoff

 

 

[Geoff13]

Another consideration on weights. There is an allowance for floats if the airframe can handle it within the regulations. Does anyone else think that it is strange that there is no allowance for a BRS if it also could fit within the design weights.

 

 

[Keith Page]

Yes that correct mtow include pilot & passenger & fuel gear .

and breakfast..

 

Regards

 

Keith Page

 

 

[ave8rr]

I am going through the same process atm. Looking at buying and the first email I have to send out is can you please tell me the MTOW and the empty weight. 90% of responses just quote manufacturers standards. I can get them off goggle. I am new to this and I want to buy something that I can fly legally with some fuel in it. There are not a lot out there that actually fit that criteria for 2 reasonably sized adults. I am not surprised at the thread that hints at some people being afraid of ramp checks..Cheers Geoff

It would be nice if the aircraft empty weight, MTOW and Rego expiry date were quoted on the RAAus register. The figs should be accurate as they would be taken off the Registration data during the registration process. I know it would mean a couple of more entries for the person entering the data.

 

 

[Dafydd Llewellyn]

Max take off weight for raa is either 544 kg or600kg. This weight of airplane plus fuel carried plus pilot and passengers and all luggage. So if you we're ready to take off and you weighed the whole lot you must be under 540 or600 kg. a 160 c weighs 300kg empty so you have 244 kg for fuel pilot passenger and luggage

WRONG. The CATEGORY weight limit was 544 Kg; it has been increased to 600 KG. The MTOW is NOT the category limit. It's what the aeroplane was designed for, and must not be exceeded regardless of the category limit.

 

 

[dutchroll]

This is all very easy to explain:

 

The MTOW - Maximum Takeoff Weight - of any aircraft is the absolute no sh*t maximum weight limit inclusive of pilots, passengers, fuel, bags, bug splatters, oil, coffee thermos and every single solitary thing which is either inside or attached to that plane, at which that plane is legal to takeoff. Notwithstanding the legality, it is most unwise, bordering on insanely stupid, to deliberately exceed an aircraft's MTOW as you are in unchartered and untested flight territory.

 

MTOW is aircraft type/model specific.

 

When an organisation talks about a "MTOW limit" they are normally talking generically, e.g., "We won't register any aircraft which have an MTOW above XXX kg".

 

 

[Dafydd Llewellyn]

So probably the last piece of info that Nev25 is left wondering about is, where does this empty weight come from......So the manufacturer of an aircraft will usually provide an empty weight in their sale brochures or online marketing gumph. Gumph is the correct terminology because it will usually be a kilo or some lighter than the lightest aircraft of any that they have delivered and probably requires the interior to be full of helium...... The weight that really matters is the empty weight that is specified in the Pilot Operators Handbook (POH) which is in the cockpit of every RAAus Aircraft. In that handbook will be the results that were obtained at the completion of the build process for that specific aircraft when the aircraft was put on the scales and weighed. The exact Kilos will be a function of how careful the builder was at managing weight from day 1 of the build process and what the fit out was in terms of avionics and other optional fit equipment.....

 

My Jabiru 230 is limited by RAAus to an MTOW of 600kg's but if the aircraft was built under VH experimental within GA then it can be MTOW = 700kgs (and instead of being the station wagon version can also have the rear 2 seats fitted..... That said I think the usual rule of thumb for seats in GA world is whatever the specification is, 2 of them to work, will need to hold young kids.... 4 adults in a J230 would not be my definition of fun, the only benefit is that the fuel load limitations are likely to mean that you wont be in back for long assuming a proper W&B config against rear seat real weight even allows it!

 

Andy

See CAO 100.7. RAA aircraft ARE NOT exempt from this.

 

 

[Guest Andys@coffs]

See CAO 100.7. RAA aircraft ARE NOT exempt from this.

Dafydd

Thanks for your post I have now spent the time to read the document you referred to (without a doubt the happiest 5 minutes tonight!!) and I'll admit to being confused.

 

In what way did my post that you referenced relate to the comment you made? I mean sure there was no <SARCASM ON> or <OFF> codes so that the reader could be left in no doubt that I was tongue in cheek, but I'll bet the majority of folks will have worked that out for themselves, so what is it that I inferred that you disliked? bear in mind that I clearly delineate marketing material and a POH, the latter I expect to contain the truth, and the basis for the truth, marketing material....not so much.....

 

Andy