# NTSB ANC19LA034: Cessna 172RG, N9715B, Ocean City, MD, July 16, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 16, 2019, 18:15 local (22:15 UTC) - Place: Ocean City, MD - Coordinates: 38.33889, -75.061668 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.3389&lon=-75.0617&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - NTSB case key (mKey): 99870 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC19LA034 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99870/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99870 - Page: https://openairdocs.org/ntsb/ANC19LA034 ## Probable cause A partial loss of power due to the liberation or failure of the No. 2 cylinder's exhaust valve. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Failure (probable cause) - [Terrain: water](https://openairdocs.org/ntsb-findings/03021020): Environmental issues › Physical environment · Contributed to outcome (probable cause) ## Analysis According to the pilot, at an altitude of 3,000 ft about 8 miles offshore while conducting fish spotting operations, the engine began to shake and lose rpm. To avoid ditching in the ocean waters, he navigated to the shoreline and the nearest airport. When it became evident that the airplane would not reach the airport, he ditched the airplane in the shallow waters of the ocean surf to avoid bystanders on the beach. The airplane sustained substantial damage to right elevator. Examination of the engine revealed that the No. 2 cylinder exhaust valve spring and guide had liberated and were located inside the damaged rocker cover. The piston and interior of the No. 2 cylinder exhibited mechanical impact damage and a hole was present in the face of the piston. The exhaust valve and exhaust valve keepers were not located. The reason for the liberation or failure of the No. 2 cylinder's exhaust valve could not be determined. ## Factual narrative On July 16, 2019, at about 1815 eastern daylight time, a Cessna 172RG airplane, N9715B, sustained substantial damage during a forced landing following a partial loss of engine power near Ocean City, Maryland. The solo commercial pilot was uninjured. The airplane was registered to and operated by the pilot, under the provisions of 14 Code of Federal Regulations Part 91 as an aerial survey flight when the accident occurred. Visual meteorological conditions prevailed and no flight plan had been filed. The flight departed Reedville Airport (VA98), Reedville, Virginia. According to the pilot, at 3,000 ft about 8 miles offshore while conducting fish spotting operations, the engine began to shake and lose rpm. In an effort to avoid ditching in the ocean waters, he navigated to the shoreline and the nearest airport. When it became evident he was unable to reach the airport, he ditched the airplane in the shallow waters of the ocean surf to avoid bystanders on the beach. The airplane sustained substantial damage to right elevator. Examination of the Lycoming O-360 series engine revealed that the engine's No. 2 cylinder exhaust valve spring and guide had liberated and were located inside the damaged rocker cover. The piston and interior of the No. 2 cylinder exhibited mechanical impact damage and a hole was present in the face of the piston. The exhaust valve and exhaust valve keepers were not located. Maintenance records revealed that the airplane's most recent annual inspection was completed on April 2, 2019. The most recent engine maintenance record entry dated June 17, 2019, indicated that the No. 2 cylinder had been removed and replaced with an overhauled cylinder. According to a mechanic who maintained the airplane, the aircraft and about 10 others flew about 1,000 hours a year for fish spotting operations. He said that stuck valves were common, as the airplanes are operated at low altitudes with rich engine fuel/air mixtures. He went on to state that the No. 2 cylinder on the accident airplane had been replaced due to a stuck valve that contacted the piston, which necessitated replacement of the entire cylinder assembly. The closest weather reporting facility is Ocean City Municipal Airport (KOXB), Ocean City, Maryland. At 1753, a METAR from KOXB was reporting in part: wind, 190° at 8 knots; visibility, 10 statute miles; sky condition, clear; temperature, 84° F; dew point 75° F; and an altimeter setting of 30.05 inches of mercury. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470) ## Aircraft - Registration: [N9715B](https://openairdocs.org/deregistered/N9715B-2022-01-08), registration cancelled 2022-01-08, S/N 172RG0986, built 1981 (OpenAirDocs) - Reported make and model: Cessna 172RG (No Series) - Registry model: [Cessna 172RG](https://openairdocs.org/model/cessna-172rg) (registry code 2072438) (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: 172RG0986 - Year built: 1981 - Engines: Lycoming O-360-F1A6 180 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 2, 2019 - Departed: VA98, Reedville, VA - Destination: Reedville, VA - Equipment: Onboard weather, Handheld GPS, Auto-pilot, ADS-B, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 23; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review March 2, 2018; seat: left; restraint: 4-point; flight hours: 3,597.5 total, 3,100 in this make and model, 3,547.5 as pilot in command, 460 in the last 90 days, 200 in the last 30 days, 4.5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 75 °F - Altimeter: 30.04 inHg ## Docket (3 files) The files NTSB released with the investigation on April 21, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99870. 5.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482763&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Memorandum for Record – Mechanic (item 2, .PDF, 131 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482764&FileExtension=.PDF&FileName=Memorandum%20for%20Record%20%E2%80%93%20Mechanic-Master.PDF - Photos (item 3, .PDF, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482765&FileExtension=.PDF&FileName=Photos-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.