GM No 3 to 21.A.708(c) Operation of Overweight Aircraft
CAA ORS9 Decision No. 1
This GM provides information and guidance with respect to permit to fly for operating an aircraft in excess of its maximum certificated take-off weight, for flight beyond the normal range over water, or over land areas where adequate landing facilities or appropriate fuel is not available.
1. GENERAL.
The excess weight that may be authorized for overweight operations should be limited to additional fuel, fuel carrying facilities, and navigational equipment necessary for the flight.
It is recommended that the applicant discuss the proposed flight with the TC holder of the aircraft to determine the availability of technical data on the installation of additional fuel carrying facilities and/or navigational equipment.
2. CRITERIA USED TO DETERMINE THE SAFETY OF ADDITIONAL FACILITIES.
In evaluating the installation of additional facilities, the CAA or the design organisation must find that the changed aircraft is safe for operation. To assist in arriving at such a determination, the following questions are normally considered:
a. Does the technical data include installation drawings, structural substantiating reports, weight, balance, new centre of gravity limits computations, and aircraft performance limitations in sufficient detail to allow a conformity inspection of the aircraft to be made?
b. In what ways does the aircraft not comply with the applicable certification specifications?
c. Are the fuel tanks vented to the outside? Are all areas in which tanks are located ventilated to reduce fire, explosion, and toxicity hazards?
d. Are the tanks even when empty strong enough to withstand the differential pressure at maximum operating altitude for a pressurized aircraft?
e. Have means been provided for determining the fuel quantity in each tank prior to flight?
f. Are shutoff valves, accessible to the pilot, provided for each additional tank to disconnect these tanks from the main fuel system?
g. Are the additional fuel tank filler connections designed to prevent spillage within the aircraft during servicing?
h. Is the engine oil supply and cooling adequate for the extended weight and range?
3. LIMITATIONS.
The following types of limitations may be necessary for safe operation of the aircraft:
a. Revised operational airspeeds for use in the overweight condition.
b. Increased pilot skill requirements.
c. A prescribed sequence for using fuel from various tanks as necessary to keep the aircraft within its centre of gravity range.
d. Notification to the control tower of the overweight take-off condition to permit use of a runway to minimize flight over congested areas.
e. Avoidance of severe turbulence. If encountered, the aircraft should be inspected for damage as soon as possible.
EXAMPLE of operating limitations which may be prescribed as part of the permit to fly:
Aircraft type: xxxxxx Model: yyyy Limitations:
1. Maximum weight must not exceed 8 150 pounds.
2. Maximum quantity of fuel carried in auxiliary tanks must not exceed 106 gallons in fwd tank, 164 gallons in centre tank, and 45 gallons in aft tank.
3. Centre of gravity limits must not exceed (fwd) +116.8 and (aft) +124.6.
4. Aerobatics are prohibited.
5. Use of autopilot while in overweight condition is prohibited.
6. Weather conditions with moderate to severe turbulence should be avoided.
7. When an overweight landing is made or the aircraft has been flown through moderate or severe turbulence while in an overweight condition, the aircraft must be inspected for damage after landing. The inspections performed and the findings must be entered in the aircraft log. The pilot must determine, before the next take-off, that the aircraft is airworthy.
8. When operated in the overweight condition, the cruising speed (Vc) shall not exceed 185 m.p.h. and the maximum speed (Vne) shall not exceed 205 m.p.h.
9. Operation in the overweight condition must be conducted to avoid areas having heavy air traffic, to avoid cities, towns, villages, and congested areas, or any other areas where such flights might create hazardous exposure to person or property on the ground.