Emergency landing, engine nacelle came loose.

Attributes
ACN	96294
Time
Date	198810
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : arb
State Reference	MI
Altitude	msl bound lower : 8000 msl bound upper : 8000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dtw tower : arb
Operator	other
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute airway : dtw enroute airway : zob
Flight Plan	IFR
Person 1
Affiliation	Other
Function	oversight : pic
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 2010 flight time type : 130
ASRS Report	96294
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	other
Supplementary
Primary Problem	Airport

Narrative:

The aircraft was brought into maintenance to have left alternator checked. It was a short/hurried day for the maintenance department which was very short handed. Director of maintenance worked on alternator while supervising other projects. As a result when the upper nacelle was attached 6 of the 15 fasteners were not secured correctly. During preflight inspection these fasteners appeared to be correctly fastened. During flight from arb to yip (10 NM) no problem was noted. In this portion of flight the airspeed was no greater than 150 mph IAS. During the level off from the climb out of yip the top nacelle came loose (at 180 mph IAS). The area around the 2 outboard nose fasteners and 2 outboard aft fasteners ripped and the outboard portion of the nacelle bent back. An immediate deceleration to VMC + 10 was initiated and cle center was notified that an immediate return to arb (closest airport) was necessary. A successful landing was made at arb with the nacelle still attached to the aircraft by 5 of the 15 fasteners. Minor sheet metal work is required to fix the nacelle. This incident could have been prevented if: 1) the maintenance department was not in a hurry and double checked their work, and 2) the pilot caught the discrepancy during the preflight. This was due to inaccurate knowledge on the appearance of the engaged fastener. Both engaged and disengaged fasteners can have the screw head lying in the horizontal position. As a result of this incident the fasteners have been more clearly marked and the correct indication has been explained to pilots and mechanics.

Original NASA ASRS Text

Title: EMERGENCY LNDG, ENGINE NACELLE CAME LOOSE.

Narrative: THE ACFT WAS BROUGHT INTO MAINT TO HAVE LEFT ALTERNATOR CHKED. IT WAS A SHORT/HURRIED DAY FOR THE MAINT DEPT WHICH WAS VERY SHORT HANDED. DIRECTOR OF MAINT WORKED ON ALTERNATOR WHILE SUPERVISING OTHER PROJECTS. AS A RESULT WHEN THE UPPER NACELLE WAS ATTACHED 6 OF THE 15 FASTENERS WERE NOT SECURED CORRECTLY. DURING PREFLT INSPECTION THESE FASTENERS APPEARED TO BE CORRECTLY FASTENED. DURING FLT FROM ARB TO YIP (10 NM) NO PROB WAS NOTED. IN THIS PORTION OF FLT THE AIRSPD WAS NO GREATER THAN 150 MPH IAS. DURING THE LEVEL OFF FROM THE CLB OUT OF YIP THE TOP NACELLE CAME LOOSE (AT 180 MPH IAS). THE AREA AROUND THE 2 OUTBOARD NOSE FASTENERS AND 2 OUTBOARD AFT FASTENERS RIPPED AND THE OUTBOARD PORTION OF THE NACELLE BENT BACK. AN IMMEDIATE DECELERATION TO VMC + 10 WAS INITIATED AND CLE CENTER WAS NOTIFIED THAT AN IMMEDIATE RETURN TO ARB (CLOSEST ARPT) WAS NECESSARY. A SUCCESSFUL LNDG WAS MADE AT ARB WITH THE NACELLE STILL ATTACHED TO THE ACFT BY 5 OF THE 15 FASTENERS. MINOR SHEET METAL WORK IS REQUIRED TO FIX THE NACELLE. THIS INCIDENT COULD HAVE BEEN PREVENTED IF: 1) THE MAINT DEPT WAS NOT IN A HURRY AND DOUBLE CHKED THEIR WORK, AND 2) THE PLT CAUGHT THE DISCREPANCY DURING THE PREFLT. THIS WAS DUE TO INACCURATE KNOWLEDGE ON THE APPEARANCE OF THE ENGAGED FASTENER. BOTH ENGAGED AND DISENGAGED FASTENERS CAN HAVE THE SCREW HEAD LYING IN THE HORIZ POS. AS A RESULT OF THIS INCIDENT THE FASTENERS HAVE BEEN MORE CLEARLY MARKED AND THE CORRECT INDICATION HAS BEEN EXPLAINED TO PLTS AND MECHS.

Data retrieved from NASA's ASRS site as of August 2007 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.