A Question for S300 Pilots

[r22butters]

In an R22 with a pilot+passenger weight exceeding 400lbs. you will most likely be beyond the forward CG limit. When you add fuel, the situation will not improve because the CG range decreases as you approach max gross weight.

 

Do you have a similar problem in the 300? The thought came up when I flew one recently, but I could not find the answer in the POH, (instuctor didn't know either).

[clay]

nope. . 600 LBS max cockpit weight.

[HelliBoy]

How could you not find an answer in the POH? Do a weight and balance calculation. Generally the 300 is much more tolerant of CoG issues than an R22, older models didnt even have limits or a chart. Just max gross and max cabin.

[Gomer Pylot]

Any POH should have a graph of CG limits vs weight. A quick glance should show if it tapers towards the top of the weight limits, or towards the bottom. Most do taper at the higher weights, but it's not universal.

[r22butters]

The weight and balance graph that is in my 300 POH, does not show CG vs. weight, nor does it have a CG range written down that changes with weight.

[rotorrodent]

In an R22 with a pilot+passenger weight exceeding 400lbs. you will most likely be beyond the forward CG limit. When you add fuel, the situation will not improve because the CG range decreases as you approach max gross weight.

 

Do you have a similar problem in the 300? The thought came up when I flew one recently, but I could not find the answer in the POH, (instuctor didn't know either).

 

I have found that landing with minimum fuel, the CG will be forward but not out of limits. (2 people). The C300 with fuel onboard, the CG will move forward as you burn off fuel.

 

Rotorrodent

[500E]

With thanks to Richard Lee

The reason there is no lateral CG published for the 269A is regulatory. The 269A was first certified under CAR/CAM 6, Rotor-craft Airworthiness; Normal Category. These were older and vastly different certification regulations than FAR Part 27 used today. You must read the entire CAR/CAM6 to fully understand the interrelationship between the various regulations but a very superficial answer can be provided using those most pertinent to this discussion.

 

CAM 6.101 pertained to weight limitations. The maximum and minimum weights at which the rotor-craft will be suitable for operation is established according to the rules. The maximum weight is based on a 170 pound person in each seat. The minimum is a single 170 pound person which is the minimum necessary to operate the 269A.

 

CG limitations could be found in 6.102. In that regulatory era, CG limitations were based on the aircraft minimum and maximum weights for which the aircraft was intended to be operated and had to be established for the most forward and aft permission for each weight. Loading instructions were only required to be provided if the center of gravity position under any possible loading condition between the maximum and minimum weights in 6.101, with assumed weights for individual passengers and crewmembers variable over the anticipated range of such weights, lies beyond:

1. The extremes selected by the applicant,

2. the extremes for which the structure has been proven,

3. The extremes for which compliance with all of the applicable flight requirements has been demonstrated.

 

CAR 6.740 defines what information shall be furnished in the Rotorcraft Flight Manual. For weight and loading distribution it states that the rotorcraft weights and center of gravity limits required by sections 6.101 and 6.102 shall be included. CAR 6.716 says essentially the same thing. Where the variety of possible loading conditions warrants, instructions shall be included to facilitate observance of the limitations. The 269A was not required to publish specific lateral limits if all applicable flight requirements could be demonstrated and no structrual limits were exceeded when there was a 170 pound person in each seat.

 

Simply stated, lateral CG limits could not be exceeded in the 269A when the aircraft was operated within the approved limits using a weight of 170 pounds for passengers and pilots; therefore the regulations at the time the aircraft was first certificated did not require Hughes to publish lateral limits.

 

Longitudinal limits were required to be established by regulation so they are provided in the flight manual.

 

The 269B and 269C were certificated as modifications to the original type certificate for the 269A so were not required to meet the additional requirements imposed by FAR Part 27.

 

When you read CAR/CAM 6 you will find many arbitrary standards used for design and performance. For instance in 6.353 controls had to be located and arranged for full and unrestricted movement for individuals ranging from 5'2" to 6'0". If you were shorter or taller the controls were never designed for you since the regulations did not require them to be so designed. You might be surprised to learn that controls could be certified for forces of 130 pound in the pedals and 100 pounds fore and aft and 67 pounds laterally for the cyclic. Imagine the complaints!

[jonny109]

I've written a basic spreadsheet that calculates the mass and balance for the 300CB. It even draws the chart for you. Download it from my website and play with the numbers.

 

http://heliinstructor.com/free-stuff/weight-balance/