[ArtieBob]

BAL is the acronym for Bauaufsicht Luft, which means air construction supervision. This was an RLM organization which had personnel stationed at the manufacturer’s plants and in addition to the inspection and approval for delivery of aircraft, might also be involved in obtaining the supply of critical materials or even becoming directly involved in the company’s production methods. IIRC, all the main serial plates I have seen for RLM aircraft had a BAL stamp indicating acceptance.

Umbau translates literally as conversion or reconstruction. The use by the RLM during WWII production refers specifically to conversions not done on the Neubau (new build) production line. The aircraft could actually have a designation indicating “Umbau”, such as a Bf 109 G-6/U4, and be listed as a neubau aircraft if the work was done as part of the new construction process. It appears that if the conversion was done after leaving the assembly plant, then the aircraft would be considered “Umbau”. A good example is the Bf 109 G-5/R2 referred to by Rasmussen in his message of on 12 Sep 05 . These Bf 109 G-5 aircraft were apparently converted to the Bf 109 G5/R2 subtype at the Erla Antwerp repair and modification facility (no new build final assembly was done at this facility during 1944) and 34 Bf 109 Aufklarer from Erla A (Antwerp) appear in the monthly reports for Umbau aircraft for July 1944. These may have been “new” aircraft, with only test flight and ferry time from the Erla final assembly plant at Leipzig to Antwerp, but Umbau is how they were identified by the RLM.

Reparatur is pretty simple ( Yes, I misspelled it earlier), meaning repairs. The RLM meaning was apparently for repair done after acceptance, away from the final assembly point. The basic concept was that production lines should be focused purely on getting new aircraft out the door and modification and repair would be done at facilities which specialized in those activities. Another term used by the RLM was, Instandsetzung, which means repair but also can mean renovate or in USA terms, overhaul.

If you want to get serious about Luftwaffe history, you really must learn to read German and have a good German-English dictionary close at hand. It helps to have a person born in Germany living across the street. Otherwise, you will only be able to read what is available in English and you will be missing a great amount of the best material that is available. Also some of the English versions leave out some of the appendices, etc. that were in the original language editions.

Best regards

Artie Bob