Quote:
Originally Posted by Matti Salonen
The Finnish Air Force normally followed the OEM established maintenance schedule. They also used the basic information in D.Luft. 3605A – B, but in locally modified form.
In Finland for DB 605 there was a 110 hours limit for a partial overhaul and 220 hours limit for complete overhaul.
Because in Finland engine running time was calculated adding test runs and ground operations to the flight time we used a life-extension based on condition of the equipment (established on a case-by-case basis, maximum 25 % for engines and 10 % for airframes).
If in the Luftwaffe system only flight time was noted in the engine running time, the Finnish model would not differ much of the Luftwaffe system especially, when D.Luft. 3605A – B does not state an exact overhaul limit but is somewhat flexible: “Nach etwa 100 Betriebsstunden” for series 0 and “Nach etwa 200 Betriebsstunden” for series 1. How much “etwa” means in running hours?
From our point of view it seems that in D.Luft. 3605A – B specified limits are a general basic rule and in real life that was interpreted by different repair shops on a case-by-case basis depending on the engine series, modification status and condition.
We have over 220 original DB 605 A –engine Lebenslaufakten in our Air Force Museum and they give a good although limited view of the repair methodology of DB 605 in Germany.
- For example 25776, which in the beginning had 100/2 overhaul limit, after repair in Germany got a new limit 75/2. (Does this mean that this engine should be sent to repair shop for partial overhaul after only 37,5 hours in the aircraft?)
- 26887 was originally DB 605 B-1 and had in the beginning an overhaul limit 75/2. It was modified to A-1 in 22.01.1943 and probably got the normal overhaul limit 100/2
- a new 76136 got in 29.01.1942 50 hour running time, but after overhaul at 56 hours in 19.09.1943 it got allowable running time up to 253 hours (overhaul limit 200 hours)
- 76782 had got in the beginning an overhaul limit 100/2, but after overhaul at 56 hours running time in 02.12.1942 it got a new allowable running time up to 252 hours (overhaul limit 200 hours). Then after a new overhaul at 125 hours in 29.07.1944 it got a new allowable running time up to 321 hours (again overhaul limit 200 hours).
According to our interpretation 100/2 in those documents means two 100 hour periods, but if you have a document, which confirms other meaning, we’ll be happy to accept that.
Unfortunately we have not yet found any document covering the content of the partial overhaul. At least it cannot be done in the fighting unit, but the engine has to be sent to a repair shop. During the war we have not found in Finnish Bf 109 any engine removal due to partial overhaul requirement, but all removals have been due to a crash or engine damage. Some of these engines had after that a partial and some complete overhaul at the Luftwaffe or Finnish repair shop.
These Lebenslaufakten include some interesting engines.
- 78874 was originally built in November 1942 as DB 628 V19 and used only 4,5 hours before being sent to overhaul. During the overhaul it was modified to DB 605 A-1 standard and got a new allowable running time up to 204 hours (overhaul limit 200 hours). This engine was sent to Finland in February 1944
- 007 00003 was similar case
- 100079 was built in July 1942 as DB 605 X and seems to have been part of DB 610. Was used in He 177 A-3, Werk.-Nr. 355065, but sent for overhaul 12.02.1943 after only 8h55’. During overhaul it was modified to DB 605 A-1
- 21077 was similar case.
DB 605 engine family has been very interesting and it would deserve an exhaustive study.
Matti
|
Yes, Thank you Matti for a good reply.
I can answer with the German information that I have in a few days, and I have many answers for you.
It is great that you have so much detail of the individual engines. I think this must be very rare. I don't know of any German individual DB 605 engine records with such detail, unless anyone has knowledge of this? I presume that the records of the Finnish Air Force engines are more complete?
The production of DB 605 engines from the DB 610 units was quite considerable, as there were a lot of them available. However, usually the rebuilt engine had a different firing order, inherited from the DB 610. The RH "605 W" component would also need rebuilding with a complete replacement rear gearcase etc as that was a complete mirror-image assembly when fitted as a DB 610 unit.
So, I will answer your points ASAP.
Cheers
Chris