I'll leave it that Brewster built junk, compared to the other manufacturers.
I think all contractors that sub-contracted had
that one company which built the lowest quality product.
For Focke Wulf it seems that Focke Wulf Soren was noted as the top quality manufacturer and was charged with building the "example" aircraft which toured the sub-contractor assembly points. This gave the sub-contractor the quality control standard.
That standard was met with varying degrees of success by sub-contractors. NDW (Dornier) was the quite frankly the worst sub-contractor and was noted for poor quality control. Problems with excessive fuel consumption, excessive vibration of the engine, and airframes not able to meet minimum performance standards are some of the investigations Focke Wulf launched into NDW. IMHO this most likely had to do with NDW's practice of further subcontracting out to manufacturers located in Neutral countries such as Sweden and Switzerland.
Supermarine also had their problems with subcontractors and the RAF notes "rouge" airframes. This is just a by product of producing a complex piece of mass manufactured machinery.
Just like any aircraft manufacturer, the Contractor has to deliver products which meet the contracted requirements. It is standard for aircraft to be inspected upon delivery and they must meet certain performance minimums before and during ferry to the accepting service. NDW had the highest number of rejected airframe from all the subcontractors. Our Focke Wulf is an NDW airframe, btw!
AFAIK, NDW FW-190's never developed a "bad reputation" with the Luftwaffe fighter force. They certainly did develop one with Focke Wulf, GmbH however.
This brings up another point on production figures. It is highly unlikely all airframes produced will see service. From any given monthly production figure, on average 50% will be rejected outright. These airframes just do not meet quality control standards and are not accepted for delivery. That is one reason initial production figures are so much lower than preceding months. That does not mean they are scrapped, just that they require additional work or refinement to bring them up to acceptance standards. The airframes then go on to be accepted and enter the accounting policies of the company. From that pool of accepted aircraft many will be tied up in maintenance stock by the gaining service. This can be as high as 75% of the airframes accepted but can vary and tends to be lower with entire assembled airframes.
This can be easily seen in the T3 production figures for the BMW801TS engine. Over 4,000 engines were delivered to the Luftwaffe from Feb. 1944 until Dec. 1944. However 75% of these engines were maintenance stock. Some 900 FW-190A9's were produced by Focke Wulf and sub-contractors and a handful of engine upgrades of older airframes to FW-190A9 standards.
So out of 735 Brewster Corsair accepted airframes with a 75% maintenance stock, we are looking at about 180 airframes in the force. Considering the sheer size of the just the USN and not counting exports, the chances of encountering a wealth of experience on "Brewster Corsairs" alone is pretty low just from the end user pool.
Just to break things down so there is not confusion on my point.
Focke Wulf and sub-contractors delivered ~340 FW190A9 airframes to the Luftwaffe by Sep. 1944. The total SE engine fighter strength of the LW is reported to be ~1810 airframes of all types in Sep 1944. Of these about 1/3 are FW-190A fighters or ~ 600 aircraft. Of the 340 FW-190A9's about 85 will be flying in the force during Sep 1944 at any given time or 14% of the total FW190A's. The rest are either down for maintenance or awaiting issue as a replacement airframe. With the engine exchange program began in July 1944 the percentage is probably a tad bit higher but our SWAG is close.
Flugzeugbestand und Bewegungsmeldungen, Jagdverbände
Just some food for thought.
All the best,
Crumpp