# NTSB CEN11LA555: Piper PA-28-180, N7689W, Millsap, TX, August 7, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 7, 2011, 13:33 local (18:33 UTC) - Place: Millsap, TX - Coordinates: 32.775554, -98.056114 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=32.7756&lon=-98.0561&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: 2 uninjured - Status: Completed, report December 11, 2012 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA/FSDO - ADs cited in the narratives: [AD 69-09-03 R3](https://openairdocs.org/ad/69-09-03-R3) (OpenAirDocs) - NTSB case key (mKey): 81430 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11LA555 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81430/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81430 - Page: https://openairdocs.org/ntsb/CEN11LA555 ## Probable cause A sudden loss of engine thrust due to the separation of a propeller blade in cruise flight due to high cycle fatigue. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Propeller system: propeller blade section](https://openairdocs.org/ntsb-findings/01046111): Aircraft › Aircraft propeller/rotor · Fatigue/wear/corrosion (probable cause); cases with it: [Piper PA-28-180, 2 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md?model=7102808), [All aircraft, 51 cases](https://openairdocs.org/ntsb-findings/01046111/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-28-180, 3 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=7102808), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) - [Emergency descent: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Piper PA-28-180, 37 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=7102808), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) ## Analysis The pilot had just leveled off to cruise flight when the airplane jerked and began to vibrate violently. The pilot secured the engine and made a forced landing on a road. A postaccident examination revealed that an 18-inch section of one of the propeller blades had separated. Metallurgical examination of the remaining blade section revealed striations on the fracture surface consistent with high-cycle fatigue. At least three crack arrest marks were observed, which was consistent with the stopping and starting of the cyclic stresses. The propeller had accumulated 165.73 hours since being overhauled in 2004. The most recent 100-hour inspection was completed about 10 months before the accident. The Federal Aviation Administration issued Airworthiness Directive (AD) 69-09-03 R3 in 1996 to prevent propeller blade tip fatigue failure. The directive required that pilots avoid continuous operation between 2150 and 2350 rpm. The failure mode of the blade was consistent with it operating in the restricted rpm range. Due to the multiple arrest marks found in the examination, the fatigue crack had propagated over multiple flight cycles. It could not be determined when the fatigue crack was initiated. ## Factual narrative On August 7, 2011, approximately 1430 central daylight time, N7689W, a Piper PA-28-180, sustained substantial damage after a section of propeller blade separated in flight and the pilot made a forced landing on a highway near Millsap, Texas. The private pilot and his passenger were not injured. The airplane was registered to the pilot and two other owners and operated by the pilot. No flight plan was filed for the flight that departed Mineral Wells Airport (MWL), about 1415, and destined for Grand Prairie Municipal Airport (GPM), Grand Prairie, Texas. Visual meteorological conditions prevailed for the flight conducted under 14 Code of Federal Regulations Part 91. The pilot reported that he was just about to level off at 3,400 feet mean sea level (msl) when the airplane made a "severe jerk" and began to vibrate violently. The pilot then observed smoke coming through the firewall and faceplates on his instrument panel began to fall off. He decided to turn off the engine by pulling the mixture control. Once the engine stopped, the pilot could see that a large section of a propeller blade was missing. He then trimmed the airplane for best glide speed and landed on a road. During the landing roll-out, the airplane's right wing struck a road sign. According to the pilot, an 18-inch long section of propeller blade was missing and the engine had broken loose from several of its motor mounts. Secondary damage to the engine and components was also reported. Metallurgical examination of the remaining blade section revealed striations on the fracture surface that were consistent with crack initiation and proporgation by high cycle fatigue. At least three crack arrest marks were observed consistent with the stopping and starting of the cyclic stresses. Examination of maintenance records revealed that the Sensenich propeller (part number 76EM8-0-60, S/N 13700K) had been overhauled on July 30, 2004, and reinstalled on the Lycoming O-360-A3A engine. The last 100 hour inspection was completed on October 1, 2010 at a total time of 165.73 hours since overhaul. The Federal Aviation Administration (FAA) issued Airworthiness Directive (AD) 69-09-03 R3 on May 15, 1996, that applied to Sensenich 76EM8 propellers mounted to Lycoming O-360-A3A engines. The AD was issued to prevent propeller blade tip fatigue failure, which could result in loss of control of the aircraft. The AD required factory inspection and reconditioning for propellers with 500 hours or more of flight time. Propellers inspected and/or reworked in accordance with that AD were to be identified with the suffix letter "K" after the serial number. The accident propeller included a "K" suffix after the serial number consistent with compliance to the AD. The AD also required the following two instructions: a) Commencing with the next flight after the effective date of this AD, do not operate the engine in continuous operation between 2150 and 2350 RPM. b) Within the next 25 hours of service (TIS) after theeffective date of this AD, mark engine tachometer with a red arc from 2150 RPM to 2350 RPM. The pilot stated that he was aware of the AD and that he had complied with the RPM restriction. ## Aircraft - Registration: [N7689W](https://openairdocs.org/deregistered/N7689W-2013-02-26), registration cancelled 2013-02-26, S/N 28-1681, built 1964 (OpenAirDocs) - Reported make and model: PIPER PA-28-180 - Registry model: [Piper PA-28-180](https://openairdocs.org/model/piper-pa-28-180) (registry code 7102808) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 28-1681 - Airframe hours: 4825 - Engines: LYCOMING O&VO-360 SER 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 1, 2010 - Departed: MWL, Mineral Wells, TX - Destination: GPM, Grand Prairie, TX - Flight plan: Unknown - Airport: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review November 9, 2010; seat: left; flight hours: 1,280 total, 110 in this make and model, 1,280 as pilot in command, 10 in the last 90 days, 8 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 99 °F, dew point 75 °F - Altimeter: 29.87 inHg - Observed at: MWL, 5 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20110807016409A](https://openairdocs.org/incident/20110807016409A), Aug 7, 2011: Piper PA-28-180, Millsap, TX, Substantial damage. On August 7, 2011, at approximately 1433 central standard time (CST), a single-engine Piper, PA28-180, N7689W, made an emergency off airport landing following… ## Docket (4 files) The files NTSB released with the investigation on October 15, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81430. 2.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 429 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40377416&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Pilot Statement (item 2, .PDF, 563 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40377417&FileExtension=.PDF&FileName=Pilot%20Statement-Redacted.PDF - Record of Conversation - Pilot (item 3, .PDF, 70 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40377418&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20Pilot-Master.PDF - Materials Laboratory 15 - Factual Report 12-090 (with 9 embedded images) (item 4, .PDF, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40376255&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2012-090%20(with%209%20embedded%20images)-Master.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.