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> Catalina Pby-5a/5
Aardvark
Posted: Dec 30 2017, 11:37 AM
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Did the RAAF convert PBY-5A's to -5 configuration by removing the undercarriage and panelling up the wheel bays.
The first image of A24-101 shows it with beaching gear fitted.
I have anecdotal advice that some were and it saved in the order of 2000 lb in weight that could be converted to extra fuel.
Does anyone have more firm advice on this.
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Shep
Posted: Dec 31 2017, 10:05 AM
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Hi Aardvark,

A Memorandum from the Air Member for Engineering and Maintenance to RAAF Headquarters, Forward Echelon, dated 3rd December, 1943, noted that PBY-5A amphibians suffered from inferior performance when compared to PBY-5 flying boats, but could carry the same maximum fuel load. It was proposed that by removing the amphibian’s undercarriage, that PBY-5 performance would therefore be restored and, as beaching gear attachments were still incorporated on the amphibians, no extra modifications would be necessary for them to become flying boats. [Enclosure 106A, Catalina Aircraft Type PBY-5A in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203].

The proposed modification not only entailed the physical removal of the landing gear, but replacing the voids with structure (trusses, frames and stringers), re-skinning and the sealing of the nose and main wheel wells. A permanent modification of this sort evidently hadn’t been done before so, a prototype modification had to be developed by Number 1 Flying Boat Repair Depot (1FBRD). [RAAF Headquarters postgram T61 of 5 Feb (1944) in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203].

The modification accordingly being developed by 1FBRD to completely seal the nose and main wheel wells was approved but, owing to the perceived possibility that RAAF Command would want the amphibian capability refitted at a later date, the “proper” modification was to be restricted to five machines and a temporary modification, developed by Saunders Roe, be installed on all other machines. [Air Member for Engineering and Maintenance memorandum SAS3505 of 2nd March, 1944, in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203].

This temporary modification proved to be unsuitable. [RAAF Headquarters postgram T381 dated 2 Mar (1944) in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203].

The temporary modification called (at least in part) for plywood boxes to be installed in the nose wheel well to mitigate against ingress of water during take-off and alighting, however this process didn’t provide a watertight seal and water inevitably entered. [RAAF Form E/E.64, Report of Failure or Defect, paragraph 19 with regard to A24-70, dated 4/2/44 in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203]. This was followed up by a finding that the temporary modification was satisfactory only at a greatly reduced weight which accordingly severely restricted the employment of the aircraft. Apparently, buoyancy was adversely affected because of the large amount of water being allowed in, such that the aircraft would ride 5 to 8 inches lower in the water which then translated into increased weight at take-off because of the excess water collected in the wheel wells. [11SQN signal T111 of 3 March (1944) in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203]. RAAF Headquarters accordingly restricted its incorporation to one aircraft only and decreed that all other machines were to have the permanent 1FBRD modification. [RAAF Headquarters signal T698 of 28 March (1944) in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203].

The 1FBRD developed permanent modification became Catalina Order No. 60 – Amphibian Landing Gear Removal (issued on 7th July, 1944).

It was applicable to aircraft A24-69 and subsequent and involved the removal of the main and nose landing wheels, actuating mechanisms and auxiliary wing fuel tanks (2020lbs), the removal of the main wheel auxiliary fuel tanks (if fitted), fittings and other odds and ends (470lbs) and then the removal of redundant hydraulic equipment (150lbs). The main wheel wells and nose wheel well were then sealed which added nearly 110lbs (including truss frames, stringers and plating) and a catwalk installed which only added 12lbs. All of this was estimated to consume 1,498 man hours and resulted in the affected PBY-5A aircraft becoming PBY-5A(M). [DTS – Publication of Catalina Order No 60 – Amphibian Landing Gear – Removal; NAA: A705, 150/4/5213. Weights from DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203].

Apparently all of the new PBY-5A aircraft (1944 allocation) being sent from the United States were equipped with auxiliary wing fuel tanks and fitted for, but not with, auxiliary wheel well fuel tanks – these being sent separately. [Conversion Drawings for PBY-5A Aircraft, dated 26th February, 1944, in DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203]. The wheel well tanks were of no use to the RAAF but, it seems, that also applied to the wing auxiliary fuel tanks.

Catalina Order No. 60 was not incorporated in all applicable aircraft. For example, A24-92, allotted to 8CU was to retain, in fully serviceable condition, its landing gear. [RAAF Headquarters Postgram TJ381PGM dated 21APR44 in DTS Catalina Aircraft Landing Gear Removal; NAA: A705, 9/30/203]. Later, it was suggested that Air Sea Rescue (ASR) aircraft also retain their landing gear.

Anyway, I hope this might be of some help to you.

You might also like to look at these digitised files on the National Archives of Australia website (each is available to download as a pdf):

DTS – Publication of Catalina Order No 60 – Amphibian Landing Gear – Removal; NAA: A705, 150/4/5213.

DTS – Catalina Aircraft – Landing Gear – Removal; NAA: A705, 9/30/203.

DTS – Catalina Aircraft PBY-5A – Landing Gear and Hydraulics; NAA: A705, 9/30/236.

Happy New Year!

Cheers,
Shep.
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Aardvark
Posted: Jan 2 2018, 09:39 AM
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Sheep Thanks for the reply.

I have copies of original WW2 USN PBY-5/5A manuals packed away somewhere.
I need to get them out and look up the fuel tanks covered in that.

Just some more research for model building.
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Gmcd
Posted: Jan 15 2018, 08:58 PM
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As a side note, during the big drought as lake Boga dried out many sets of Catalina main gears were discovered sitting on the lake bed where they had apparently been used as weights for mooring buoys. After 60 something years on the bottom of the lake they were still is remarkably good condition, some even still leaking a little oil.
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