MU2B-60 pilot reported that an improperly reset air conditioning circuit breaker caused smoke to ent...

Attributes
ACN	1412166
Time
Date	201612
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	MU-2B 60 Marquise
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Route In Use	Vectors
Flight Plan	IFR
Component
Aircraft Component	Circuit Breaker / Fuse / Thermocouple
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 4 Flight Crew Total 3300 Flight Crew Type 600
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Maintenance Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

Narrative:

I had just picked up the airplane from maintenance. While it was in the shop; per normal procedures certain circuit breakers are pulled; including the air conditioning circuit breaker (the maintenance was unrelated to the air conditioner). Although they pushed the circuit breaker back in; it was not fully seated. This caused hot bleed air to come through the lines; igniting the residual engine oil in those lines. This caused smoke to enter the cabin. This occurred on initial climbout during the handoff from tower to approach. I informed approach of the situation and was provided vectors for the ILS approach; after which I landed without incident. Arff responded; but there was nothing for them to do.the approach and tower controllers; and arff; all did an excellent job. Contributing to this occurrence was the fact that because of the low altitude; there had not yet been an opportunity for much cabin differential pressure to build up; so the normal procedures for clearing smoke from the cockpit (selecting ram air; opening the pilot's storm door; etc.) were of little help. Fortunately the entire event only lasted about 5-6 minutes; so I was able to get the plane back on the ground before visibility of the flight instruments became a serious issue. After I landed; maintenance reset the circuit breaker; tested the system; and I proceeded back to base about an hour later without further incident.

Original NASA ASRS Text

Title: MU2B-60 pilot reported that an improperly reset air conditioning circuit breaker caused smoke to enter the cabin.

Narrative: I had just picked up the airplane from maintenance. While it was in the shop; per normal procedures certain circuit breakers are pulled; including the air conditioning CB (the maintenance was unrelated to the air conditioner). Although they pushed the CB back in; it was not fully seated. This caused hot bleed air to come through the lines; igniting the residual engine oil in those lines. This caused smoke to enter the cabin. This occurred on initial climbout during the handoff from tower to approach. I informed approach of the situation and was provided vectors for the ILS approach; after which I landed without incident. ARFF responded; but there was nothing for them to do.The approach and tower controllers; and ARFF; all did an excellent job. Contributing to this occurrence was the fact that because of the low altitude; there had not yet been an opportunity for much cabin differential pressure to build up; so the normal procedures for clearing smoke from the cockpit (selecting RAM air; opening the pilot's storm door; etc.) were of little help. Fortunately the entire event only lasted about 5-6 minutes; so I was able to get the plane back on the ground before visibility of the flight instruments became a serious issue. After I landed; maintenance reset the CB; tested the system; and I proceeded back to base about an hour later without further incident.

Data retrieved from NASA's ASRS site 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.