Aircraft Accident/Incident Report

Tacoma, Washington 98401
Thursday, June 2, 2005 6:00 PDT

NTSB Narrative Summary Released at Completion of Accident

During an annual inspection, a crack was found in the lower wing spar cap of the subject aircraft. That discovery was reported via email to the NTSB's Northwest Regional Office. It was later determined that a fatigue crack had initiated at a rivet hole on the horizontal surface of the right wing lower spar cap, and propagated through approximately 80 percent of that surface. The NTSB materials laboratory determined that there was no evidence of inclusions, discontinuities, corrosion pitting, or material defects at the crack origins. All dimensional measurements were within engineering drawing specifications, and hardness and conductivity parameters for the aluminum alloy specified for the wing spar cap material were within material tolerances. During the investigation it was determined that at the time the crack was detected, the aircraft had flown 5,273 hours. Of that total time, approximately 1,100 hours were flown as part of a low-level pipeline patrol mission. It was further determined that as part of the certification process, Piper Aircraft had determined that the "general use" safe time in service (TIS), adjusted with a scatter pattern of eight, was 10,723 hours for the wing structure. The certification process did not include determination of a safe time in service when any portion of the aircraft's life included being used in a "pipeline survey" mission profile. The investigation also determined that the two rivet holes through which the crack passed (one of which was the point of origin) were the locations where two of the rivets that held the lower wing skin on in an area addressed by Piper Service Bulletin 796B, Part One. This service bulletin was published by Piper to address "loose and working rivets along the lower spar cap." In part, the bulletin states, "If this condition exists, and is left uncorrected over an extended period of time, the structural integrity of the wing could be compromised." The actions delineated in this service bulletin had not been performed on this aircraft (N27PG) even though loose and working (smoking) rivets were found at the subject location on the lower skins of both wings.

NTSB Probable Cause Narrative

The initiation and propagation of a fatigue crack, over 5,273 hours of cyclic in-flight usage, through approximately 80 percent of the aircraft's right wing spar lower cap.

Event Information

Type of Event Incident
Event Date 6/2/2005
Event Day of the Week Thursday
Time of Event 600
Event Time Zone Pacific Daylight Time
Event City Tacoma
Event State WASHINGTON
Event Country --
Zipcode of the event site 98401
Event Date Year 2005
Event Date Month 6
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude 471605N
Event Location Longitude 1223441W
Event Location Airport --
Event Location Nearest Airport ID --
Indicates whether the acc/inc occurred off or on an airport --
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness --
Investigator's weather source Unknown
Time of the weather observation
Direction of event from weather observation facility (degrees) --
Weather Observation Facility ID --
Elevation of weather observation facility --
Distance of event from weather observation facility (units?) --
Time Zone of the weather observation --
Lighting Conditions --
Lowest Ceiling Height --
Lowest Non-Ceiling Height --
Sky/Lowest/Cloud Conditions --
Sky Condition for Lowest Ceiling --
Visibility Runway Visual Range (Feet) --
Visibility Runway Visual Value (Statute Miles) --
Visibility (Statute Miles) --
Air Temperature at event time (in degrees celsius) --
Dew Point at event time (in degress fahrenheit) --
Wind Direction (degrees magnetic) --
Variable Wind Indicator --
Wind Speed (knots) --
Wind Velocity Indicator --
Wind Gust Indicator Unknown
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) --
Density Altitude (feet) --
Intensity of Precipitation --
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries --
On Ground, Minor Injuries --
On Ground, Serious Injuries --
Injury Total Fatal --
Injury Total Minor --
Injury Total None 1
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 20385
NTSB Notification Source PAC Northwest Adjusters
NTSB Notification Date Jun 2 2005 12:00AM
NTSB Notification Time --
Fiche Number and/or location -used to find docket information DMS
Date of most recent change to record Oct 3 2006 2:46PM
User who most recently changed record NTSB\JOHB
Basic weather conditions --
FAA District Office Seattle FSDO

Aircraft Involved

Aircraft #1

Aircraft Registration Number N27PG
NTSB Number SEA05IA115
Missing Aircraft Indicator --
Federal Aviation Reg. Part Unknown
Type of Flight Plan filed --
Flight plan Was Activated? --
Damage Minor
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Piper
Aircraft Model PA-46-350P
Aircraft Series Identifier --
Aircraft Serial Number 4622104
Certified Max Gross Weight 4300
Aircraft Category Airplane
Aircraft Registration Class --
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 6
Number of Engines 1
Fixed gear or retractable gear Retractable
Aircraft, Type of Last Inspection Annual
Date of Last Inspection --
Airframe hours since last inspection 0
Airframe Hours 5273
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name Wade H. Perrow
Aircraft Owner Street Address --
Aircraft Owner City Gig Harbor
Aircraft Owner State WA
Aircraft Owner Country USA
Aircraft Owner Zipcode 98335
Operator is an individual? No
Operator Name --
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? Yes
Operator Street Address --
Operator City --
Operator State --
Operator Country --
Operator Zip code --
Operator Code --
Owner has at least one certificate None
Other Operator of large aircraft? --
Certified for Part 133 or 137 Operation --
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Non-scheduled
Indicates Domestic or International Flight Domestic
Operator carrying Pax/Cargo/Mail Passenger Only
Type of Flying (Per_Bus / Primary) --
Second Pilot on Board --
Departure Point Same as Event No
Departure Airport Code --
Departure City --
Departure State --
Departure Country --
Departure Time --
Departure Time Zone --
Destination Same as Local Flt --
Destination Airport Code --
Destination City --
Destination State --
Destination Country --
Specific Phase of Flight Unknown
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Feb 5 2013 12:08PM
User who most recently changed record broda
Since inspection or accident Last Inspection
Event Location Runway Number and Location --
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --