AAIB Report - Microlight Accident
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I would add that Genghis posted some very helpful stuff, for those who have a staple diet of pies, about getting your seat limit increased. The post gave the maths involved in proving that you were safe and I was very grateful to read it.
Six hours a week for six months, down the gym, means that I am now a mere slip of a pilot at 76kg
Six hours a week for six months, down the gym, means that I am now a mere slip of a pilot at 76kg
I wonder just how many light aircraft or public transport aircraft have seats and belts approved for over 20 stone people at +/-4.5g vertically, +/- 3g sideways and +9g forwards?
G
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Genghis,
CS-23 and CS-VLA make interesting reading regarding seat weights.
CS-23 goes into great detail about loadings in various directions for seats and seat belts.
However, the general weight on the seat used "to show compliance with requirements" seems to be just that - a notional weight that is used to show compliance - not a limitation. If it was a limitation then loking at the part where minimum weight is specified, if taking that to be a restriction one could never fly the aircraft with that seat empty!
Since minimum weights per seat may be specified to show compliance with the requirements, are they saying that seats can not be empty even if the C of G is within limits?
My reading of the specified weights (which are only options under CS-23) are that they are used to prevent designers using overly light individuals to acheive unrealistic figures.
However, that aside, if the CAA say that it is a restriction then it is a restriction and organisations interested in flight safety need to consistently and constantly send out a clear message that the rules are to be complied with..........until they can get the rules changed.
Regards,
DFC
CS-23 and CS-VLA make interesting reading regarding seat weights.
CS-23 goes into great detail about loadings in various directions for seats and seat belts.
However, the general weight on the seat used "to show compliance with requirements" seems to be just that - a notional weight that is used to show compliance - not a limitation. If it was a limitation then loking at the part where minimum weight is specified, if taking that to be a restriction one could never fly the aircraft with that seat empty!
Since minimum weights per seat may be specified to show compliance with the requirements, are they saying that seats can not be empty even if the C of G is within limits?
My reading of the specified weights (which are only options under CS-23) are that they are used to prevent designers using overly light individuals to acheive unrealistic figures.
However, that aside, if the CAA say that it is a restriction then it is a restriction and organisations interested in flight safety need to consistently and constantly send out a clear message that the rules are to be complied with..........until they can get the rules changed.
Regards,
DFC
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My reading of the specified weights (which are only options under CS-23) are that they are used to prevent designers using overly light individuals to acheive unrealistic figures.
- Max cockpit weight; full fuel
- Max cockpit weight; no fuel
- Min cockpit weight; full fuel
- Min cockpit weight; no fuel
Genghis seems to know about these things, perhaps he'll clarify.
MadamB
The 86kg value (previously 90kg) in Section S used for W&CG requirements is still there for weight requirements, but there's been a partial de-coupling.
So, a microlight must have an empty weight not greater than MAUW - 86kg/seat - 1hrs fuel at maximum continuous power. This is identical to the requirement in CS.VLA for non-aerobatic light aeroplanes.
However, whilst it was originally coupled also to the CG and structural requirements, that's been de-coupled in recent years out of necessity. So, It's now possible to use any higher (than 86kg) weight the designer selects so long as at the permitted seat / fuel loadings the aircraft remains within CG limits, and the structural requirements are met for the seat/harness/surrounding-structure at those higher seat limits.
If you look at CS.23 or FAR-23 (or part 25), they are subtly different in that the empty weight issue is still there (albeit using slightly different numbers, typically 77kg/seat and 30 minutes fuel), but there is no CG issue - it's assumed that the pilots of part 23 aeroplanes are capable of doing W&CG calcs (whether this is true or not is a moot point, but they've been trained to
)
G
So, a microlight must have an empty weight not greater than MAUW - 86kg/seat - 1hrs fuel at maximum continuous power. This is identical to the requirement in CS.VLA for non-aerobatic light aeroplanes.
However, whilst it was originally coupled also to the CG and structural requirements, that's been de-coupled in recent years out of necessity. So, It's now possible to use any higher (than 86kg) weight the designer selects so long as at the permitted seat / fuel loadings the aircraft remains within CG limits, and the structural requirements are met for the seat/harness/surrounding-structure at those higher seat limits.
If you look at CS.23 or FAR-23 (or part 25), they are subtly different in that the empty weight issue is still there (albeit using slightly different numbers, typically 77kg/seat and 30 minutes fuel), but there is no CG issue - it's assumed that the pilots of part 23 aeroplanes are capable of doing W&CG calcs (whether this is true or not is a moot point, but they've been trained to
)G
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" it's assumed that the pilots of part 23 aeroplanes are capable of doing W&CG calcs (whether this is true or not is a moot point, but they've been trained to"
Decades of flipping through things like the crash comics suggest that more training ie CPL rather than PPL leads to more problems in this area.
Decades of flipping through things like the crash comics suggest that more training ie CPL rather than PPL leads to more problems in this area.
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Genghis,
You said: So, a microlight must have an empty weight not greater than MAUW - 86kg/seat - 1hrs fuel at maximum continuous power. This is identical to the requirement in CS.VLA for non-aerobatic light aeroplanes
To my reading all that does is set a maximum weight for the aircraft structure (including engine).
Where in relation to the above limitation does it say that having a structure that meets that requirement, it is illegal for each seat to be filled by 96Kg individuals and the fuel load reduced so that MTOM and C of G limitations are complied with?
Does the seat limit only arise because the designer has designd a placard showing a limitation?
Having had some time to think about it, I think that I would prefer to be sitting on a seat whose legs would crumple under me in an accident than be sitting on a seat that would hold firm and transmit all the shock load to my spine.
Regards,
DFC
You said: So, a microlight must have an empty weight not greater than MAUW - 86kg/seat - 1hrs fuel at maximum continuous power. This is identical to the requirement in CS.VLA for non-aerobatic light aeroplanes
To my reading all that does is set a maximum weight for the aircraft structure (including engine).
Where in relation to the above limitation does it say that having a structure that meets that requirement, it is illegal for each seat to be filled by 96Kg individuals and the fuel load reduced so that MTOM and C of G limitations are complied with?
Does the seat limit only arise because the designer has designd a placard showing a limitation?
Having had some time to think about it, I think that I would prefer to be sitting on a seat whose legs would crumple under me in an accident than be sitting on a seat that would hold firm and transmit all the shock load to my spine.
Regards,
DFC
S 23 Load distribution limits
a) The ranges of weight and c.g. within which the aeroplane is to be safely operated must be selected by the applicant.
b) The c.g. range must not be less than that which corresponds to the weight of each occupant, varying between a minimum of 55 kg for the pilot alone up to the maximum placarded weight with a pilot and passenger, together with a variation in fuel contents from zero to full fuel. The placarded maximum [occupant] weight must be not less than [86 kg] per person. (See AMC S 23 b).)
S 25 Weight limits
Maximum weight. The maximum weight must be established so that it is:
a) not more than:
1) the highest weight selected by the applicant;
2) the design maximum weight, which is the highest weight at which compliance with each applicable structural loading condition and each applicable flight requirement is shown.
b) not less than the weight which results from the empty weight of the aeroplane, plus a weight of occupant(s) of [86] kg for a single-seat aeroplane, or [172] kg for a two-seat aeroplane, plus the required minimum equipment, plus fuel [for at least 60 minutes flight at maximum continuous power.]
c) [not less than the weight which results with one (86 kg pilot) occupant, required minimum equipment and maximum fuel. (See AMC S 25 c).)]
a) The ranges of weight and c.g. within which the aeroplane is to be safely operated must be selected by the applicant.
b) The c.g. range must not be less than that which corresponds to the weight of each occupant, varying between a minimum of 55 kg for the pilot alone up to the maximum placarded weight with a pilot and passenger, together with a variation in fuel contents from zero to full fuel. The placarded maximum [occupant] weight must be not less than [86 kg] per person. (See AMC S 23 b).)
S 25 Weight limits
Maximum weight. The maximum weight must be established so that it is:
a) not more than:
1) the highest weight selected by the applicant;
2) the design maximum weight, which is the highest weight at which compliance with each applicable structural loading condition and each applicable flight requirement is shown.
b) not less than the weight which results from the empty weight of the aeroplane, plus a weight of occupant(s) of [86] kg for a single-seat aeroplane, or [172] kg for a two-seat aeroplane, plus the required minimum equipment, plus fuel [for at least 60 minutes flight at maximum continuous power.]
c) [not less than the weight which results with one (86 kg pilot) occupant, required minimum equipment and maximum fuel. (See AMC S 25 c).)]
S 561 General
a) The aeroplane, although it may be damaged in emergency landing conditions, must be designed as prescribed in this paragraph to protect each occupant under those conditions.
b) The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a crash landing when proper use is made of belts and harnesses provided for in the design, in the following conditions:
1) Each occupant experiences, separately, ultimate inertia forces corresponding to the accelerations shown in the following:
c) Each aeroplane with a retractable landing gear must be designed to protect each occupant in a landing with wheel(s) retracted under the following conditions:
1) A downward ultimate inertia force corresponding to an acceleration of 3 g;
2) A coefficient of friction of 0.5 at the ground.
d) Except as provided in S 787, the supporting structure must be designed to restrain, under loads up to those specified in sub paragraph b) 1) of this paragraph, each item of mass that could injure an occupant if it came loose in a minor crash landing.
e) Where the failure of all or part of the engine mounting structure could result in an engine following a trajectory that could pass through any part of the normal crew accommodation or fuel tanks, the attachment structure must be designed to withstand an ultimate inertia force corresponding to an acceleration of 15 g in that direction.
a) The aeroplane, although it may be damaged in emergency landing conditions, must be designed as prescribed in this paragraph to protect each occupant under those conditions.
b) The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a crash landing when proper use is made of belts and harnesses provided for in the design, in the following conditions:
1) Each occupant experiences, separately, ultimate inertia forces corresponding to the accelerations shown in the following:
c) Each aeroplane with a retractable landing gear must be designed to protect each occupant in a landing with wheel(s) retracted under the following conditions:
1) A downward ultimate inertia force corresponding to an acceleration of 3 g;
2) A coefficient of friction of 0.5 at the ground.
d) Except as provided in S 787, the supporting structure must be designed to restrain, under loads up to those specified in sub paragraph b) 1) of this paragraph, each item of mass that could injure an occupant if it came loose in a minor crash landing.
e) Where the failure of all or part of the engine mounting structure could result in an engine following a trajectory that could pass through any part of the normal crew accommodation or fuel tanks, the attachment structure must be designed to withstand an ultimate inertia force corresponding to an acceleration of 15 g in that direction.
S 786 Protection from injury
a) [Each seat and its supporting structure must be so designed that in the event of a collapse of any or all of the landing gear units the risk of serious injury to the occupant is minimised.] (See AMC S 786 a).)
b) Rigid structural members or rigidly mounted items of equipment, must be padded where necessary to protect the occupant(s) from injury during minor crash conditions.
a) [Each seat and its supporting structure must be so designed that in the event of a collapse of any or all of the landing gear units the risk of serious injury to the occupant is minimised.] (See AMC S 786 a).)
b) Rigid structural members or rigidly mounted items of equipment, must be padded where necessary to protect the occupant(s) from injury during minor crash conditions.
[AMC S 786 a) (Interpretative Material)
The seat support structure should be designed, as far as is practicable, so as to prevent spinal or other serious injuries to the occupant in a minor crash landing in which the landing gear may have collapsed. It is recommended that rigid structural members are not located in a position likely to cause injury in such a crash landing and that energy absorbent materials should be used under the seat structure to reduce the impact loads being applied to the occupant’s spine.]
The seat support structure should be designed, as far as is practicable, so as to prevent spinal or other serious injuries to the occupant in a minor crash landing in which the landing gear may have collapsed. It is recommended that rigid structural members are not located in a position likely to cause injury in such a crash landing and that energy absorbent materials should be used under the seat structure to reduce the impact loads being applied to the occupant’s spine.]
S 1519 Weight and c.g.
a) The maximum weight determined under S 25 a) must be established as an operating limitation.
b) The c.g. limitations determined under S 23 must be established as operating limitations.
c) The empty weight and the corresponding c.g. positions must be determined in accordance with S 29.
a) The maximum weight determined under S 25 a) must be established as an operating limitation.
b) The c.g. limitations determined under S 23 must be established as operating limitations.
c) The empty weight and the corresponding c.g. positions must be determined in accordance with S 29.
S 1557 Miscellaneous markings and placards
a) Baggage compartment. Each baggage compartment must have a placard stating
the loading limitations.
b) Fuel and oil filler openings. The following apply:
1) Fuel filler openings must be marked at or near the filler cover with the minimum
fuel grade and fuel/oil ratio.
2) Oil filler openings must be marked at or near the filler cover:
i) with the grade; and
ii) if the oil is detergent or non detergent.
c) Fuel tanks. The usable fuel capacity of each tank must be marked either at the selector or on the gauge (when provided) or on the tank if this is translucent and visible to the pilot in flight.
d) In-flight engine starting. A placard must be provided stating any limitations to be observed during in-flight engine starting.
e) Loading
1) The following data must be placarded in each aeroplane so as to be plainly visible to the pilot:
i) Empty weight [(actual);]
ii) Maximum weight;
iii) Maximum and minimum cockpit load;
iv) Cockpit load conditions for two-seater flown solo;
v) [Fuel load limitations for the range of allowable cockpit loads.]
2) [Removable ballast.] If removable ballast is used, the place for carrying ballast
must have a placard stating instructions for the proper placement and securing of the removable ballast under each loading condition for which removable ballast is necessary.
f) Aerobatic manoeuvres. A placard prohibiting aerobatic manoeuvres and intentional spinning must be plainly visible to the pilot.
a) Baggage compartment. Each baggage compartment must have a placard stating
the loading limitations.
b) Fuel and oil filler openings. The following apply:
1) Fuel filler openings must be marked at or near the filler cover with the minimum
fuel grade and fuel/oil ratio.
2) Oil filler openings must be marked at or near the filler cover:
i) with the grade; and
ii) if the oil is detergent or non detergent.
c) Fuel tanks. The usable fuel capacity of each tank must be marked either at the selector or on the gauge (when provided) or on the tank if this is translucent and visible to the pilot in flight.
d) In-flight engine starting. A placard must be provided stating any limitations to be observed during in-flight engine starting.
e) Loading
1) The following data must be placarded in each aeroplane so as to be plainly visible to the pilot:
i) Empty weight [(actual);]
ii) Maximum weight;
iii) Maximum and minimum cockpit load;
iv) Cockpit load conditions for two-seater flown solo;
v) [Fuel load limitations for the range of allowable cockpit loads.]
2) [Removable ballast.] If removable ballast is used, the place for carrying ballast
must have a placard stating instructions for the proper placement and securing of the removable ballast under each loading condition for which removable ballast is necessary.
f) Aerobatic manoeuvres. A placard prohibiting aerobatic manoeuvres and intentional spinning must be plainly visible to the pilot.
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Thanks Genghis.
So as I read your quotes, the designer chooses the limitations which must be placarded. The minimum weight chosen (and placarded) can not be greather than 55Kg but could be zero. The maximum weight chosen must be at least 86Kg but could be more. It is all up to the designer who could design and aircraft that could be operated with 1 50Kg pilot or 2 100Kg pilots provided that was determined during the design and testing and the limits were placarded and the overal microlight limitations were acheived.
Isn't the microlight supposed to be a simple aircraft!
Thanks again.
Regards,
DFC
So as I read your quotes, the designer chooses the limitations which must be placarded. The minimum weight chosen (and placarded) can not be greather than 55Kg but could be zero. The maximum weight chosen must be at least 86Kg but could be more. It is all up to the designer who could design and aircraft that could be operated with 1 50Kg pilot or 2 100Kg pilots provided that was determined during the design and testing and the limits were placarded and the overal microlight limitations were acheived.
Isn't the microlight supposed to be a simple aircraft!
Thanks again.
Regards,
DFC
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I have always been impressed by the excellent dispassionate nature of AAIB reporting. But recently there has been a lapse. As an example, in the 10/2005 G-HASO report, the AAIB made inappropriate recommendations for mods to the Thielert diesel engine, after FOD ingestion. The LBA (German 'CAA' responsible for the aircraft's certification) rejected their proposals, pointing out that the 'protection' offered by the mod was against a mechanic leaving a tool in the previously filtered air inlet - and aviation mechanics should not do that! Well done LBA and a win for common sense!
Unfortunately, the AAIB report tried to justify their recommendation in the face of this rejection. Methinks they protesteth too much.
Dave
Unfortunately, the AAIB report tried to justify their recommendation in the face of this rejection. Methinks they protesteth too much.
Dave
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LINEFINDER100 - I have to agree. I read most AAIB reports that come my way, especially those relating to GA, and find an element of "conjecture" creeping in. Can any one surmise why this may be the case or are we simply mistaken?
Speaking as one who had a bit of a serious "up and downer" with the said Mr McDermid of the AAIB, I am of the view that the organisation has lost it's way.
I spoke to Mr McDermid's senior a few days later and expressed my concern over the apparent lack of impartiality shown. The response I received was luke warm and reflected an apparent lack of interest in only reporting the hard facts relating to the case in question.
Whether the resultant bias is due to deliberate managment intervention, poor direction or by a lack of interest by the staff I do not know. I do feel very uncomfortable about such a well-respected organisation squandering it's hard won reputation in this way though.
VP
I spoke to Mr McDermid's senior a few days later and expressed my concern over the apparent lack of impartiality shown. The response I received was luke warm and reflected an apparent lack of interest in only reporting the hard facts relating to the case in question.
Whether the resultant bias is due to deliberate managment intervention, poor direction or by a lack of interest by the staff I do not know. I do feel very uncomfortable about such a well-respected organisation squandering it's hard won reputation in this way though.
VP
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Well a manslaughter prosecution has now been mounted, see the new thread I started here: http://www.pprune.org/forums/showthread.php?t=208990
(mods - feel free to merge threads).
WRT to the previous posts on this subject, I have a general point to make. I feel some posters are missing the point. Microlighting is a *sport*. It's wrong thinking, IMHO, to compare the safety of microlights to transport cat. aircraft. 'Paying passenger' notwithstanding. I'd expect to be, and feel, moderately safe on board a high-end coach on the motorway. I'd expect to be, and feel, less safe as a 'paying passenger' in a souped-up WRX hurtling through a forest on a 'rally experience' ride. Extreme example, but I trust the point is made.
R1
(mods - feel free to merge threads).
WRT to the previous posts on this subject, I have a general point to make. I feel some posters are missing the point. Microlighting is a *sport*. It's wrong thinking, IMHO, to compare the safety of microlights to transport cat. aircraft. 'Paying passenger' notwithstanding. I'd expect to be, and feel, moderately safe on board a high-end coach on the motorway. I'd expect to be, and feel, less safe as a 'paying passenger' in a souped-up WRX hurtling through a forest on a 'rally experience' ride. Extreme example, but I trust the point is made.
R1
