I wonder how many of the those who own one of the SEPS with a max. landing weight less than the MTOW would burn off fuel before landing if the need arose – and given that it would probably be a pretty urgent need given the margins are small (rough running engine immediately after take off) wether they would prefer to expidite the landing?
You would also need to think about “demonstrating” a take off at MTOW followed by a few T and Gs.
In my aircraft the max landing weight is 50kg less than MTOW [1200kg], so if I had an emergency/pan situation I would not hesitate to get down immediately. The landing gear is designed to take a firm landing at max landing weight, so it should not be a problem if I landed anything like reasonably… and if not, due to an emergency then the affect on landing gear would not be a concern.
And if not an urgency situation and the landing conditions were reasonable I would likely assume I could do a normal (gentle) landing, so also not putting unreasonable stress on the landing gear.
DA40drvr wrote:
The landing gear is designed to take a firm landing at max landing weight
If so, what grounds remain for stating the MLW below MTOW?
Yes, it is interesting in the types mentioned the MLW is very close but less than the MTOW. It makes one wonder if the limitation is solely seen to be conencted with the strength of the u/c and the extent to which the calculations include the consequence of a “firm” landing. In the alternative it could be a consequence of the approach speed but this seems very unlikely since this would have to be a more general limitation.
Once again understanding the reasons, the margins and calculations would seem a better basis for assessing the consequence of the limitation.
Fuji_Abound wrote:
It makes one wonder if the limitation is solely seen to be conencted with the strength of the u/c and the extent to which the calculations include the consequence of a “firm” landing.
Consider the capacity of the brakes for stopping the heavier plane without overheating.
As a very active Jetprop owner, I feel compelled to relate my own experiences of operating inside and outside the POH MTOW envelope.
Firstly to dispel some myths. I do not routinely fly overweight. With a BEW of 3,106Lbs my aircraft gives me 1,234 Lbs of Useful load to be split between fuel and payload. Full fuel weighs in at just over 1,059lbs, with a reserve range of 1,000Nm so there is flexibility for managing fuel versus payload to stay within the limits.
Having said that, and as mentioned in a previous thread I have on numerous occasions flown under a ferry permit with an extended range fuel bladder in the cabin that takes me anywhere from 400-600lbs over MTOW.
The ability to do so is very prescriptive, with a whole supplemental manual to the POH that amends the limitations section and at no time exceeds CG limits which I stick to religiously. Out of CG envelope is the killer IMHO.
During the original ferry flight from Florida to Bangkok, the aircraft experienced a loss of control during a phugoid excursion at FL270 where the aircraft pulled +6G and -1.5G over a 3 second period whilst being 500lbs over gross at the time. A structural survey following a precautionary landing afterward revealed no damage.
During the early part of the acquisition process, I was blessed to be mentored by Mr. PA46, an extremely experienced PA46 test pilot, instructor, DAR, and member of the original PA46 design team. Jason will know the credentials of this individual, who developed the Ferry tank install design.
He was onboard during the incident and performed the post incident survey and analysis with the FAA.
He certainly earned his money that night… The presence of a G-Meter on board at the time is part of his SOP which he insists all his students have, and I continue to use.
Since then I have used the ferry tank numerous times under the ferry permit with full confidence that providing I respect the additional limitations the original design protections will apply.
My ability to do so is borne from an intimate knowledge of this particular airframe thanks to Mr. PA46, supplemented by over 1,500 flying hours in her, its maintenance record, and my own risk assessment based on my own abilities.
I would not entertain any of the above in any other airframe including another Jetprop without the same level of scrutiny and calculation. My point being that it can be done given the proper considerations.
As a footnote, there is a strong rumor that a long awaited Gross weight increase of 300lbs is on its way for the Jetprop…
E
eal’s post is excellent.
@mh: Excuse me for coming back to this only now. For the sake of clarity I will be, for once, top-posting.
Your comments are welcome and indeed much appreciated – but they only illustrate my point. All show planes going down with overload, but none has overload as the prime cause of failure. The prime cause is either the CoG out of bounds – which several contributors have mentioned as far worse than overweight – or pilots doing silly things that would end in disaster anyway, only the overweight brought disaster even quicker. For one example, exceeding Vne by no less than 53 km/h is a certain recipe for disaster, at whatever gross weight.
mh wrote:
Sorry, I can’t let this go uncommented.Jan_Olieslagers wrote:
If you see the typical Rotax-powered two-seater with two adults in it, you can bet it is overweight by at least 10%. This may aggravate other problems, but I have yet to see an accident report for this category of plane where overweight was cited as the prime cause.I know, this is a widespread thinking among microlight pilots, but there are, depending on the aircraft, enormous changes in flight dynamics and handling, if overloaded. Many microlights tend to load the crew and baggage, sometimes the fuel, too, aft of the cog and thus overloading the aircraft may result in critical slow flight characteristics. This is explicitly described here where a Rans S6 was stalled after buzzing a lake. Here is another stall / spin accident where the pilot flew “family visiting turns” with a CG, way beyond the aft limit, generated by overloading the aircraft. The spin investigation even at the allowed aft cg limit showed, that this aircraft would develop a spin without much notice. The BFU has many similar reports, where heavy overloaded microlights were part of stall / spin accidents. In many occurrences, the MTOM of 472,5kg was overloaded up to 580kg without fuel. You don’t have to be an aeronautical engineer to see, that that can’t be a sound modus operandi. But if you are, you are amazed by the amount of “muppets” among the pilots and how close they often come to killing someone out of ignorance.
Furthermore, it seems that the neglect of mass limitation does impact the handling of other limitations, like V_NE. Here is anexample of a flight, where the V_NE was exceeded by 53 kph, inducing elevator flutter and subsequent partial desintegration of the elevator. There are more examples like that in the BFU database.
Jan_Olieslagers wrote:
All show planes going down with overload, but none has overload as the prime cause of failure.
This is wrong. In those planes you don’t have much room for choice when placing your loads. It’s not a Cessna 207, which you could load out of balance within weight limitations. Weight and balance, and with it altering flight characteristics, were a major contributor to those crashes.
You won’t find a single aircraft accident that has been linked just to one failure, as you might know. Or do you extrapolate your reasoning on other accidents, too, for instance saying VFR in IMC had never been a prime cause of failure, since the losing of control over the aircraft or flying too low for the terrain was what caused the crashes?
Neglect is a dangerous game in aviation.
All show planes going down with overload, but none has overload as the prime cause of failure. The prime cause is either the CoG out of bounds – which several contributors have mentioned as far worse than overweight – or pilots doing silly things that would end in disaster anyway, only the overweight brought disaster even quicker.Quote
I agree with this. Unless the plane is so heavy that it cannot get airborne before the end of the runway, or cannot out climb terrain, simply being overweight will not be a single cause of an accident. Overweight, and mishandling is much more likely a cause of an accident, in which case, the pilot did not fly the aircraft as required for the condition. Now if the pilot took off overweight, they made themselves a test pilot anyway, but that does not mean that the aircraft was necessarily unflyable.
Out of C of G limits is much more likely a factor in accidents, but again, there is a tolerance for out of C of G, but the consequences of mishandling are very much more severe in terms of sudden loss of control, or inability to recover lost control.
Most planes I know can be easily misloaded, and a few will reach a C of G limit before they can be loaded to gross weight, which is dangerous. A deHavilland Beaver on floats, and some Stinsons on floats suffer this characteristic. THe Cessna 207 and Piper Cherokee Six are surprisingly loadable, as they both have nose baggage comartments to allow you to balance them well. On the other hand, the Cessna 310R, with a massive nose baggage compartment is easily misloaded forward. Sometimes there is no C of G capacity for any nose compartment load.
