# NTSB ERA10IA254: Piper PA 46-350P, N46PT, Owensboro, KY, April 25, 2010 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: April 25, 2010, 16:40 local (21:40 UTC) - Place: Owensboro, KY - Coordinates: 37.738609, -87.166664 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.7386&lon=-87.1667&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report July 12, 2011 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: Piper Aircraft Inc., FAA/FSDO - NTSB case key (mKey): 75954 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA10IA254 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75954/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75954 - Page: https://openairdocs.org/ntsb/ERA10IA254 ## Probable cause A failure of the pilot's side window due to undetected cracking around the lower aft portion of the storm window cutout. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Windows-windshield system: flight compartment windows](https://openairdocs.org/ntsb-findings/01035610): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Piper PA 46-350P, 1 case](https://openairdocs.org/ntsb-findings/01035610/cases.md?model=7104620), [All aircraft, 42 cases](https://openairdocs.org/ntsb-findings/01035610/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Piper PA 46-350P, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=7104620), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis While flying at 15,000 feet in the pressurized airplane, the pilot's side window blew out. The pilot successfully diverted to a nearby airport and landed uneventfully after performing an instrument approach in instrument meteorological conditions. Postincident examination of the window revealed that the primary fracture, which ultimately resulted in the in-flight loss of the window, exhibited signatures of preexisting cracking. The airframe manufacturer had previously issued a service bulletin that detailed inspections of the window for cracking, and while the cracking observed on the incident window occurred outside of the area called out in the service bulletin, review of the incident airplane's maintenance records showed no evidence that any portion of the service bulletin had ever been complied with. ## Factual narrative On April 25, 2010, about 1640 central daylight time, a Piper PA 46-350P, N46PT, incurred minor damage when the pilot side window shattered and departed the airplane, while in cruise flight near Owensboro, Kentucky. The certificated commercial pilot and the two passengers were not injured. Instrument meteorological conditions prevailed, and the flight was operating on an instrument flight rules flight plan. The personal flight, which departed Southern Illinois Airport (MDH), Carbondale, Illinois, was destined for Smith Reynolds Airport (INT), Winston Salem, North Carolina. The flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. According to the pilot, he had just leveled the airplane at 15,000 feet mean sea level, and was adjusting the engine to the cruise power setting. The airplane was pressurized, and all of the instruments were indicating normally. The pilot's side window then suddenly "blew out," depressurizing the airplane immediately. The pilot reported that his headset was "sucked out" of the airplane. The pilot utilized the headset installed on the copilot's side of the airplane and advised air traffic control of the situation. Air traffic control subsequently issued radar vectors, and cleared him for an instrument landing system approach to Owensboro-Daviess County Airport (OWB), Owensboro, Kentucky. The pilot landed the airplane without further incident. The remaining portion of the window, which was estimated to be about 30-percent of its total surface area, was forwarded to the NTSB Materials Laboratory for further examination. According to the Materials Laboratory Factual Report, a primary overstress fracture emanated from the radius of the pilot's side window, storm window cutout, and followed a path aft and downward (relative to the window's installed position on the airplane). Other fractured pieces along the top and forward edge of the window exhibited fractures attributed to the secondary overstress cracks associated with the overall in-flight loss of the window. Detailed examination of the primary fracture near the point of initiation showed a locus of preexisting craze cracks along the lower aft radius of the storm window cutout. The cracks had a thumbnail shape and emanated from the edge radius or on the flat face of the storm window cutout edge. On December 13, 2006, the airframe manufacturer issued Service Bulletin (SB) Number 1175, which detailed requirements for repetitive inspections and/or replacement of the pilot side window. An inspection of the lower aft corner of the storm window for cracking was required after the first 350 hours in service, and every 50 hours thereafter. If cracks were found, the window would require replacement, and continued inspection at the previously stated intervals. In May 2007, the airframe manufacturer superseded the service bulletin with a revision (SB 1175A) that allowed for the installation of a newly designed pilot side window, which eliminatedthe storm window and upon installation, and relieved the repetitive inspection requirement. The primary fracture noted on the incident airplane's pilot's side window occurred outside, but adjacent to, the inspection called out in the SB. Following the incident, the airframe manufacturer released a revised SB 1175B, which expanded the inspection area and incorporated a photograph from the incident window illustrating an example of the cracking mechanics should inspect for. Review of the incident airplane's available airframe maintenance records by a Federal Aviation Administration inspector revealed no evidence that either the inspection or replacement of the window had been performed in compliance with any revisions of the SB. ## Aircraft - Registration: [N46PT](https://openairdocs.org/aircraft/N46PT), registered now, S/N 4622108, built 1990 (OpenAirDocs) - Reported make and model: PIPER PA 46-350P - Registry model: [Piper PA 46-350P](https://openairdocs.org/model/piper-pa-46-350p) (registry code 7104620) (OpenAirDocs) - Registry engine: [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series) (registry code 41533, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 4622108 - Engines: LYCOMING TIO-540 SER 310 horsepower reciprocating - Damage: Minor damage - Flight: Personal, Part 91 - Operator: T & K LLC - Registered owner: T & K LLC - Airworthiness certificate: Standard, Normal - Departed: MDH, Carbondale, IL - Destination: INT, Winston-Salem, NC - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review February 1, 2010; seat: left; flight hours: 1,900 total, 230 in this make and model, 40 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 13 knots, gusting 19 - Visibility: 5 statute miles - Lowest ceiling: 1,100 ft broken - Temperature: 57 °F, dew point 55 °F - Altimeter: 29.38 inHg - Observed at: OWB ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20100425032779I](https://openairdocs.org/incident/20100425032779I), Apr 25, 2010: Piper PA 46-350P, Owensboro, KY, Minor damage. Pilot reports that during cruise flight, 15000 ft., 188 KTS TAS, 27 degree f. OAT, the cockpit left side window broke and the aircraft depressurized. All other… ## Other investigations on N46PT (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB CHI07LA035](https://openairdocs.org/ntsb/CHI07LA035), Dec 3, 2006: Piper PA 46-350P (N46PT), Atlanta, GA, substantial damage. Probable cause: The exceedance of airplane design stress limits when the pilot did not maintain aircraft control after his attention was diverted to the right side attitude indicator during cruise flight. An… ## Docket (6 files) The files NTSB released with the investigation on May 16, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75954. 4.0 MB in all. - Pilot's Statement (item 1, .PDF, 40 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40347635&FileExtension=.PDF&FileName=Pilot%27s%20Statement-Master.PDF - Investigation Photographs (item 2, .PDF, 2 photos, 729 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40347634&FileExtension=.PDF&FileName=Investigation%20Photographs-Master.PDF - Materials Laboratory Factual Report 10-080 (item 3, .PDF, 6 photos, 988 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40335043&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%2010-080-Master.PDF - Piper Service Bulletins (1175, 1175A, and 1175B) (item 4, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40347636&FileExtension=.PDF&FileName=Piper%20Service%20Bulletins%20(1175,%201175A,%20and%201175B)-Master.PDF - Record of Correspondence - FAA Inspector (item 5, .PDF, 49 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40347914&FileExtension=.PDF&FileName=Record%20of%20Correspondence%20-%20FAA%20Inspector-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 750 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40347632&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.