Narrative:

After starting the right engine for taxi; I turned both packs on and immediately noticed a very strong oil/machinery smell. I isolated each pack individually; and the condition remained. I shut both packs down; and the condition abated. It was a very strong oil smell not related to engine exhaust induction from the aircraft exterior. The fumes were certainly coming from the bleed system. The same symptoms occurred with the subsequent number 1 engine start as well. In order to stop the fumes; I had to shut both packs down for several minutes until the engine oil temperature was stabilized. Fumes are entering the bleed air system for the first several minutes of engine operation.I suggest[ed] that after starting the number 2 engine and experiencing fumes; and diagnosing if the source were the packs or the bleed system; I shut down both packs for 2 minutes and retried the packs. The fumes resumed. I suspected that if I let the engine oil temperature stabilize after warming up to normal idle temperature; the fumes may stop. I shut both packs down until the engine oil temperature stabilized; and put the packs back on. No fumes. After the number 1 engine start; I waited to put the packs on until the number 1 engine oil temperature stabilized and put both packs on. No fumes. The next morning we operated the same aircraft. With each engine start before putting the packs on I waited until the engine oil temperatures ceased warming up and stabilized. This proved to be effective; and we experienced no fumes. My specific suggestions are: do not operate the packs until engine oil has stabilized after engine start. Place a box-check option under event details for fumes on reports to track fume occurrences and numbers which exhibit fumes on engine startup.

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Original NASA ASRS Text

Title: A B757-200 First Officer let the engine oil temperature stabilize before turning the packs ON in order to prevent oil fumes from entering the air conditioning system.

Narrative: After starting the right engine for taxi; I turned both packs ON and immediately noticed a very strong oil/machinery smell. I isolated each pack individually; and the condition remained. I shut both packs down; and the condition abated. It was a very strong oil smell not related to engine exhaust induction from the aircraft exterior. The fumes were certainly coming from the bleed system. The same symptoms occurred with the subsequent Number 1 Engine start as well. In order to stop the fumes; I had to shut both packs down for several minutes until the engine oil temperature was stabilized. Fumes are entering the bleed air system for the first several minutes of engine operation.I suggest[ed] that after starting the Number 2 Engine and experiencing fumes; and diagnosing if the source were the packs or the bleed system; I shut down both packs for 2 minutes and retried the packs. The fumes resumed. I suspected that if I let the engine oil temperature stabilize after warming up to normal idle temperature; the fumes may stop. I shut both packs down until the engine oil temperature stabilized; and put the packs back on. No fumes. After the Number 1 Engine start; I waited to put the packs on until the Number 1 Engine oil temperature stabilized and put both packs on. No fumes. The next morning we operated the same aircraft. With each engine start before putting the packs on I waited until the engine oil temperatures ceased warming up and stabilized. This proved to be effective; and we experienced no fumes. My specific suggestions are: Do not operate the packs until engine oil has stabilized after engine start. Place a box-check option under Event Details for fumes on reports to track fume occurrences and numbers which exhibit fumes on engine startup.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.