Aircraft Cargo Compartments Classification

 

Aircraft cargo compartments classification subject is related to the aircraft airworthiness certification. The major risk is fire and fire class, regulators required many standards to protect cargo compartment from fire risk. This can be achieved by fire protection and suppression systems.

Aircraft Cargo Compartments Classification 

Aircraft Cargo compartments are classified [ in most national airworthiness requirements ] as follows:

 

Class A Aircraft Cargo Compartment 

A Class A cargo or baggage compartment is one in which:

1. the presence of a fire would be easily discovered by a crew member while at his or her station; and
2. each part of the compartment is easily accessible in flight.

Class B Aircraft Cargo Compartment 

A Class B cargo or baggage compartment is one in which:

1. there is sufficient access in flight to enable a crew member to effectively reach any part of the compartment with the contents of a hand fire extinguisher.
2. when the access provisions are being used, no hazardous quantity of smoke, flames or the extinguishing agent will enter any compartment occupied by the crew or passengers; and
3. there is a separately approved smoke detector or fire detector system to give warning at the pilot or flight engineer station.

Class C Aircraft Cargo Compartment 

A Class C cargo or baggage compartment is one not meeting the requirements for either  - Class A or B compartment but in which:

1. there is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station;
2. there is an approved built-in fire-extinguishing system controllable from the pilot or flight engineer station;
3. there are means of excluding hazardous quantities of smoke, flames, or extinguishing agent from any compartment occupied by the crew or passengers; and
4. there are means of controlling ventilation and draughts within the compartment so that the extinguishing agent used can control any fire that may start within the compartment.

Class D Aircraft Cargo Compartment 

A Class D cargo or baggage compartment is one in which:

1. a fire occurring in it will be completely confined without endangering the safety of the aircraft or the occupants;
2. there are means of excluding hazardous quantities of smoke, flames, or other noxious gases from any compartment occupied by the crew or passengers;
3. ventilation and draughts are controlled within each compartment so that any fire likely to occur in the compartment will not progress beyond safe limits; and
4. consideration is given to the effect of heat within the compartment on adjacent critical parts of the aircraft.
   

 For compartments of 14.2 m3 or less, an airflow of 42.5 m3 per hour is acceptable.

 

Class E Aircraft Cargo Compartment 

>A Class E cargo compartment is one on aircraft used only for the carriage of cargo and in which:

1. there is a separate approved smoke or fire detector system to give warning at the pilot or flight engineer station;
2. there are means of shutting off the ventilating airflow to or within the compartment, and the controls for these means are accessible to the flight crew in the crew compartment;
3. there are means of excluding hazardous quantities of smoke, flames, or noxious gases, from the flight crew compartment; and
4. the required crew emergency exits are accessible under any cargo loading conditions.

Now, I am sure you understood each cargo compartment class. But you don't know where are their locations on the aircraft body.

 

Aircraft Cargo Compartment Locations 

Location of Class A Cargo Compartment 

Class A cargo compartments are small cargo compartments that may be located between the flight deck and the passenger cabin or adjacent to the galley area or at the back of the aircraft.

 

Location of Class B Cargo Compartment 

A Class B cargo compartment is usually much larger than a Class A cargo compartment and can be located in an area remote from the flight deck. Class B cargo compartments are found on “combi” aircraft between the flight deck and the passenger cabin or behind the passenger cabin at the rear of the aircraft. 

 

Note.— A “combi” aircraft is one in which both cargo and passengers are carried on the main deck.

 

Location of Class C Cargo Compartment 

It's large in volume, the volume of a Class C cargo compartment is usually larger than Class A or B and such cargo compartments are generally found under the floor in wide-bodied aircraft. A Class C cargo compartment may have two fire extinguishing systems, enabling a second charge of extinguishant to be fired into the cargo compartment sometime after the fire has initially been controlled by the first charge.

 

Location of Class D Cargo Compartment 

Instead of being equipped with fire detection and extinguishing systems, Class D cargo compartments are designed to control a fire by severely restricting the supply of oxygen.  Class D cargo compartments are to be found under the passenger cabin floor on most jet transport aircraft. However, it must be appreciated that certain dangerous goods are themselves, oxygen producers. Therefore, it cannot be assumed that a fire in a Class D cargo compartment will necessarily self-extinguish.

 

 

Location of Class E Cargo Compartment 

A Class E cargo compartment normally comprises the entire main deck compartment of a cargo aircraft.

 

Conventional Passenger Aeroplane

A conventional passenger aeroplane is usually fitted with either Class C or Class D cargo compartments under the passenger cabin.

Cargo Aeroplane

A cargo aeroplane is usually fitted with a Class E main deck cargo compartment and with Class D and/or Class C underfloor cargo compartments.

Combi  Aeroplane

A “combi” aeroplane is usually fitted with a Class B main deck cargo compartment, either in front or behind the passenger cabin and with a Class C and/or Class D cargo compartment under the floor.

Smaller Commuter Aeroplane

The smaller commuter aeroplane, if not fitted as a conventional passenger aeroplane with a Class D cargo compartment, could be equipped with only a Class A cargo compartment, usually positioned in the area adjacent to the flight deck.
 

Helicopters

Helicopters are capable of carrying freight either in the main cabin (in a Class A cargo compartment) or under the cabin floor. The cargo compartment under the floor has no classification and the compartment is not capable of withstanding fire for any length of time. 

Some helicopters have cargo compartments which are at the rear of the aircraft and which are inaccessible from inside the helicopter. These cargo compartments are usually small and they are not fitted with any fire detection systems, extinguishing systems or liners.

Summary 

For certification, cargo compartments must comply with different performance standards. Which are mentioned above.