# NTSB CEN09LA132: Grumman American Avn. AA-5B, N28862, Milford, IN, January 5, 2009

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: January 5, 2009, 11:15 local (16:15 UTC)
- Place: Milford, IN
- Coordinates: 41.401111, -85.855552 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.4011&lon=-85.8556&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report July 14, 2009
- Report: Approved by Office Director
- NTSB office: Central Region
- Parties: FAA-South Bend FSDO, Sensenich Propeller Company, Inc.
- ADs cited in the narratives: [AD 69-09-03 R3](https://openairdocs.org/ad/69-09-03-R3) (OpenAirDocs)
- NTSB case key (mKey): 73229
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN09LA132
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/73229/pdf
- Page: https://openairdocs.org/ntsb/CEN09LA132

## Probable cause

A loss of engine thrust due to the separation of a section of one of the propeller blades as a result of fatigue failure of the propeller because of corrosion. Contributing to the accident was the failure of the mechanic to detect and address the propeller corrosion during the annual inspection.

## 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 · Failure (probable cause); cases with it: [Grumman American Avn. AA-5B, 2 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md?model=3960105), [All aircraft, 51 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md)
- [Inspection: scheduled/routine inspection](https://openairdocs.org/ntsb-findings/02061520): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Grumman American Avn. AA-5B, 1 case](https://openairdocs.org/ntsb-findings/02061520/cases.md?model=3960105), [All aircraft, 167 cases](https://openairdocs.org/ntsb-findings/02061520/cases.md)
- [Propeller system: propeller blade section](https://openairdocs.org/ntsb-findings/01046111): Aircraft › Aircraft propeller/rotor · Fatigue/wear/corrosion (probable cause); cases with it: [Grumman American Avn. AA-5B, 2 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md?model=3960105), [All aircraft, 51 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md)
- [Propeller system: propeller blade section](https://openairdocs.org/ntsb-findings/01046111): Aircraft › Aircraft propeller/rotor · Inadequate inspection (probable cause); cases with it: [Grumman American Avn. AA-5B, 2 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md?model=3960105), [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: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Grumman American Avn. AA-5B, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=3960105), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md)
- [Enroute-cruise: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338); cases with it: [Grumman American Avn. AA-5B, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=3960105), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md)
- [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Grumman American Avn. AA-5B, 7 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3960105), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)

## Analysis

The airplane was in cruise flight when the pilot heard a "loud bang followed by a violent vibration." He secured the engine and executed a forced landing to an open field. A postaccident examination revealed that a 20-inch length of one of the propeller blades had separated. Metallurgical examination revealed a fatigue failure of the propeller blade initiating from an area of corrosion. Corrosion pitting was observed over the entire cambered surface of the blade. The propeller had accumulated 2,326 hours total time in service. The most recent annual inspection was completed approximately 2 months prior to the accident. Federal Aviation Administration publications and the manufacturer's documentation recommended a detailed visual inspection of the propeller for corrosion during an aircraft annual inspection.

## Factual narrative

On January 5, 2009, about 1115 eastern standard time, a Grumman AA-5B Tiger, N28862, was substantially damaged following an in-flight separation of a propeller blade and a forced landing near Milford, Indiana. The instructional flight was being operated under 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed. The private pilot and flight instructor were not injured. The local flight departed about 1045. The private pilot stated that the airplane was in cruise flight at 3,500 feet mean sea level (msl) when he heard a "loud bang followed by a violent vibration." He secured the engine and "pulled the nose of the airplane up to stop the rotation of the propeller." He subsequently executed a forced landing to an open field. A post accident examination revealed that a 20-inch length of one of the blades had separated from the 2-bladed, fixed pitch propeller. The separated section was not recovered. Secondary damage to the engine assembly, engine mounts and firewall was also observed. Metallurgical examination of the remaining portion of the blade revealed a chordwise fracture approximately 18 inches from the hub centerline (20 inches from the tip). The fracture surface exhibited features consistent with fatigue failure that covered about 70-percent of the area. The remaining surface area appeared consistent with an overload failure. Fatigue striations emanated from an area of corrosion on the cambered side of the blade. Visual inspection using low-powered magnification revealed corrosion pitting distributed over the entire cambered surface of the blade. Maintenance records revealed the propeller was installed new on the accident airplane in September 1983. It was subsequently reconditioned in May 1987. The most recent annual inspection was completed on October 31, 2008. At the time of the accident, the propeller had accumulated 2,326 hours total time in service, with 8 hours since the annual inspection. Airworthiness Directive (AD) 69-09-03 R3, effective May 15, 1996, 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. No subsequent AD's had been issued related to the accident propeller. The manufacturer issued Service Bulletin R-15A on October 4, 1989, recommending inspection and repair procedures to address corrosion issues. Specifically, the service bulletin stated that propeller blades should be inspected for corrosion during annual or 100-hour inspection procedures. Any corrosion should be repaired or the propeller reconditioned depending upon the extent and severity of the corrosion. Service Bulletin R-17 was issued March 16, 1999, which noted the Federal Aviation Administration's (FAA) prior approvalfor an increase in the time between propeller overhaul/reconditioning cycles (TBO). The TBO was increased from 1,000 hours total flight time to 2,000 hours for normal and utility operations provided that the specific propeller had not sustained damage that required immediate attention. Aerobatic operations remained at 1,000 hours TBO. However, regulations do not require compliance with TBO limits for non-commercial operations. In these cases, continued airworthiness is based on the condition of the propeller. FAA Advisory Circular (AC) 20-37E, Aircraft Propeller Maintenance, states that a detailed inspection is completed at each annual inspection or as required by the aircraft maintenance procedures. The detailed inspection should include visual examination of the propeller blades using ten-power (10X) magnification for questionable areas. The visual examination is to look for excessive wear and erosion, damage, nicks, cracks, corrosion, lightning strike, or ground strike.

## Aircraft

- Registration: [N28862](https://openairdocs.org/deregistered/N28862-2009-03-30), registration cancelled 2009-03-30, S/N AA5B0869, built 1978 (OpenAirDocs)
- Reported make and model: GRUMMAN AMERICAN AVN. CORP. AA-5B
- Registry model: [Grumman American Avn. AA-5B](https://openairdocs.org/model/grumman-american-avn-aa-5b) (registry code 3960105) (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: AA5B0869
- Airframe hours: 3377
- Engines: LYCOMING O&VO-360 SER 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Airworthiness certificate: Standard, Utility; Standard, Normal
- Last inspection: Annual, October 31, 2008, 8 hours before
- Departed: 25IN, Howe, IN
- Destination: GSH, Goshen, IN
- Airport: GSH, Goshen Muni

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 34; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review January 5, 2009; seat: left; flight hours: 282 total, 138 in this make and model, 211 as pilot in command, 3 in the last 90 days, 2 in the last 30 days, 1 in the last 24 hours
- Flight instructor; age 79; injuries: none; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review June 1, 2007; seat: right; flight hours: 4,000 total, 50 in this make and model, 3,000 as pilot in command, 10 in the last 90 days, 5 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 230° at 7 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 21 °F, dew point 16 °F
- Altimeter: 30.00 inHg
- Observed at: GSH, 7 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 20090105012609A](https://openairdocs.org/incident/20090105012609A), Jan 5, 2009: Amrgen AA5B, Kosciuko Count, IN, Substantial damage. (-23) Pilot reported that during his bi-annual flight review he and his CFI were on a northern heading off wolf lake VOR, level at 3500 ft. they heard a loud…

## Other investigations on N28862 (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 ATL80DKG09](https://openairdocs.org/ntsb/ATL80DKG09), Jul 5, 1980: Grum Amer AA5-B (N28862), Americus, GA, substantial damage

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.

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