Revival of the Combi Freighters?

[Self loading bear]

I clearly have no experience in the airfreight market so therefore perhaps this stupid question:

What is your opinion on the chances of a revival of the Combi Freighters?
- Any wide body type?
Are STCs already available?
- Fitting a large cargo door aft
How long would that take?
- What else that I am clearly not aware of?

[champair79]

The SAA 747 Heldeberg accident near Mauritius...

Basically re-certifying a combi is prohibitively expensive I believe due to the fire suppression system. The only ones that exist are ones that were built as combis (I.e KLM 747s). I’m sure someone will be around to give you more detail. But yes, in these times having a fleet of combis would be ideal although for how long who knows.

champ

[deltahotel]

Most pure freighters don’t have fire suppression on the main deck. They do have fire detection in the form of smoke detectors, so in the absence of these there would need to be some form of fire watch personnel.

The other big issue without a cargo door is loading/unloading times as everything has to go in via a normal pax door.

There is some more discussion of this in R&N about 737 freighters and, I think, a picture of a 777 with all the seats/overheads stripped out.

[TURIN]

Far too many 757SF conversions about.
If there's cargo to be carried the likes of DHL etc have the market covered on thin routes where a combi would be useful.

[742]

Originally Posted by deltahotel

Most pure freighters don’t have fire suppression on the main deck. They do have fire detection in the form of smoke detectors, so in the absence of these there would need to be some form of fire watch personnel.

The other big issue without a cargo door is loading/unloading times as everything has to go in via a normal pax door.

There is some more discussion of this in R&N about 737 freighters and, I think, a picture of a 777 with all the seats/overheads stripped out.

Pure freighters deal with a main deck fire by depressurizing and staying at altitude (FL250 in the checklists that I have flown). You can not do that with passengers in the mix.

[deltahotel]

I get that, but I’m assuming that a combi will either work as a freighter or pax but not at the same time.

[SMOC]

Originally Posted by deltahotel

I get that, but I’m assuming that a combi will either work as a freighter or pax but not at the same time.

In that role they should be referred to as 'convertible' not combination, combined "combi" but often combi is used for both.

For example Boeing calls a convertible a -200C while a combi is -200M

[B2N2]

There’s is such a thing as simply not carrying hazmat when carrying passengers.
No lithium batteries nor electronics with installed batteries.

*as far as a combo is concerned the pax would sit in the rear with the freight portion forward.
So freight can be loaded through a large freight door and pax board from the rear.
Assuming a 73 configuration.
I’ve recently read Lufthansa Technik is working on a 380 Freighter combi, pax in upper deck and cargo on lower deck.

[TFE731]

Originally Posted by deltahotel

I get that, but I’m assuming that a combi will either work as a freighter or pax but not at the same time.

If that case it is called a QC (quick change) not a combi.

[FlyingStone]

Originally Posted by B2N2

I’ve recently read Lufthansa Technik is working on a 380 Freighter combi, pax in upper deck and cargo on lower deck.

This would require either having lower deck as Class C cargo compartment with associated fire detection and suppression system or lobby for regulation change to allow Class E on combi aircraft.

​I can't imagine what the weight penalty would be for a Class C fire suppression system for such a large volume as the lower deck of A380, and then to add it on top of A380's less than stellar useful load. This could be mitigated by "ETOPS-like" restriction of maximum time from an adequate airport. But funny enough, A380 can't really fit anywhere a B777 or a B747 can, so more troubles ahead.

Class E would be even a more difficult puzzle to solve, as fire suppression is essentially done by de-pressurising the aircraft once fire condition is detected, followed by a flight at ~FL250 until reaching diversion airport. So either they separate the aircraft into two pressure vessels, allowing separate pressure control between lower and upper deck, or to equip the passenger cabin with similar oxygen system that is available to flight crew on freighter aircraft, again with significant weight penalty.

No doubt, the technical solution for this problem exists. But I don't think it will come even close to being economically viable.

[dixi188]

Originally Posted by TFE731

If that case it is called a QC (quick change) not a combi.

Not all convertable Pax/Cargo aircraft are QC. The old B707-320C took about a week to change fron Cargo to Pax IIRC.

[Self loading bear]

All thanks for your reactions so far.
I have done some googling myself:

2 KLM 747 Combi’s have been put in service again.
The Martinair MD11s were true convertibles.

E class fire suppression (By means of depressurization) is indeed not allowed in combi’s.
I don’t think a pressure resistant floor is technical feasible for the A380.
Gas/smoketight will probably already be a challenge??

Only Class A, B, (firefighting by flight engineer or additional crew) or C class (Halon)
The last is expensive and heavy.
The extra firefighters for A and B are already on board by means of the cabin crew.
but this will require additional space and walkways between pallets.

It will be clear an A380 combi will not load same as a full freighter 747 or 777 but how much pallets and tons of weight could probably be loaded on the lower deck?

[GAZIN]

Main deck cargo fire suppression does exist, and would seem to be quite viable, especially if the cargo is containerised. At least one US integrator has such a system on its larger wide bodies.

[tdracer]

After the Heldeberg accident, the regulations concerning "combi" type aircraft were changed. I'm not familiar with the details, but those who are have told me it would close to impossible to certify a new combi aircraft under the latest regulations. I'm thinking retrofit (e.g. A380 combi) would be even harder since you couldn't design some of the stuff in.
All the combi's currently in operation (e.g. 747-400 Combi) were certified before the regulations were changed. I seriously doubt we'll ever see any more new build combi aircraft.

[ZFT]

Having walked through the rebuild wreckage of the Heldeberg and seen the obvious intensity of the fire, there is no way you would ever get me on any Combi style aircraft.

The regulations were changed for 159 very good reasons.