The document below about help given to Sgt. Phillip Leonard Pepper by four German women, Mrs. Riedl, Miss Pompetzki, Mrs. Heckenleichtner, and Mrs. Hellmeier in Munich from March 1943 to May 1945 is all that I found at National Archives II about German helpers of Allied airmen. But it certainly is intriguing. The source for citation purposes is UD163: Records re Polish, Swiss, Danish, Yugoslav and German Helpers, 1945-1946, Box 626, Location: 290/55/22/2. Following it see the M.I.9 report on Sgt. Pepper.
Thanks to researcher John Clinch, we also have Sgt. Pepper’s M.I.9/S/P.G. (G) report 3014., shown below, which goes into some detail about his experiences.
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If anyone has any information to add to the above, I would like to hear from them.
WWII Netherlands Escape Lines 
My grandfather came by when an American airman who was shot down on his way to Regensburg and wanted to escape to Luxemburg was discovered. He took him to his place. My grandmother gave him dry clothes and made some hot soup for him. They never thought of hiding him, just acting in a humane way until he would be arrested anyway. My grandfather was accused by the Gestapo and sentenced to five months in prison. His judge found it especially apalling, that the airman had even got a Schnaps.
Some weeks before, I found out the name of the man from the Gestapo-files: SSgt William E. Roberts, 390th BG, ball turret gunner in 42-30017. No other traces.