# NTSB CHI05FA048: Beech S35, N5631K, Herman, WI, December 25, 2004 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: December 25, 2004, 10:21 local (16:21 UTC) - Place: Herman, WI - Coordinates: 44.267955, -89.617012 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=44.2680&lon=-89.6170&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed, report January 31, 2006 - Report: Approved by Office Director - Parties: FAA, Beech, Teledyne Continental - NTSB case key (mKey): 60771 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI05FA048 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/60771/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=60771 - Page: https://openairdocs.org/ntsb/CHI05FA048 ## Probable cause The installation of the improper cylinder base packing seals by maintenance personnel resulting in the loss of lubriation and subsequent failure of the number four connecting rod/bearing. A factor associated with the accident was the trees that the airplane contacted during the forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, cruise - normal - maintenance,top overhaul - performed, other maintenance personnel - engine assembly,other - improper (cause) - maintenance,installation - improper, other maintenance personnel (cause) - fluid,oil - starvation - engine assembly,bearing - failure,total - engine assembly,connecting rod - failure,total - Forced landing, emergency descent/landing - In flight collision with object, emergency descent/landing - object - tree(s) (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - ground - Fire, other ## Analysis The airplane collided with trees and terrain during a forced landing following a loss of engine power. Approximately 8 minutes after taking off, the pilot reported to air traffic control that the cabin of his airplane was filling with smoke and he was diverting to a near-by airport. The airplane contacted 30 to 40 foot tall trees which bordered an open field. The airplane then contacted the terrain and a post impact fire ensued. Inspection of the engine revealed two holes in the crankcase near the number four cylinder with the number four piston rod separated from the crankshaft. Teardown of the engine revealed five cylinder deck stud nuts were missing and the number five cylinder seventh stud had sheared. The crankshaft, counterweights, and rod bearings exhibited thermal damage which was most prominent at the number four cylinder connecting rod journal. Material from the number four connecting rod bearing was fused to the crankshaft journal displacing the oil tube toward the number three main journal. The cylinders had been removed and overhauled approximately 380 hours prior to the accident. The cylinder base packings on all of the cylinders were flattened and extruded between the base of the cylinders and the crankcase. The cross section diameter of the packings was larger than a sample packing, part number 641066, which is used on IO-520-BA engines. The cross section diameter of the base packings that were removed from the engine were similar in diameter to those used on the O-470 series engines. ## Factual narrative HISTORY OF FLIGHT On December 25, 2004, at 1021 central standard time, a Beech S35, N5631K, collided with trees and the terrain in Herman, Wisconsin, following a loss of engine power during flight. The airline transport pilot and a passenger were fatally injured. The airplane was substantially damaged by impact with the terrain and a post impact fire. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions on an instrument flight rules (IFR) flight plan. The airplane departed the Manitowoc County Airport (MTW), Manitowoc, Wisconsin, at 1010, en route to the Lewis University Airport (LOT), Romeoville, Illinois. The pilot was attempting to divert to the Sheboygan Memorial Airport (SBM), Sheboygan, Wisconsin, when the accident occurred. Records compiled by the Federal Aviation Administration (FAA) indicate the following: At 0545, the pilot requested weather information through a direct user access terminal (DUATS). At 0620, the pilot filed an IFR flight plan and requested weather information through DUATS. At 0703, the pilot called the Green Bay Flight Service Station for an IFR weather briefing for a flight from MTW to LOT. At 1006, Green Bay (GRB) air traffic control tower (ATCT) issued an IFR clearance to N5631K for a flight from MTW to LOT. At 1010, the pilot reported to GRB ATCT that N5631K was airborne. At 1011, radar contact was established with N5631K. At 1012, N5631K was issued a frequency change to contact the Chicago air route traffic control center (ZAU). At 1012:51, N5631K contacted ZAU and reported being at 4,000 feet. At 1018:42, N5631K reported to ZAU that they had an emergency. The controller asked what the emergency was and the pilot replied that the cabin was filling with smoke and they were heading for Sheboygan. The controller instructed N5631K to descend and maintain 3,000 feet. The controller also informed N5631K that SBM was 5 miles away at their 10 o'clock position. At 1019:32, the controller asked the pilot if he had the airport in sight. The pilot replied that the airport was in sight. At 1019:36, the controller cleared N5631K for the visual approach to the airport and told the pilot that he could cancel his IFR flight plan through N800MW. The pilot of N5631K responded, "three one kilo." This was the last radio contact with N5631K. At 1025:06, another airplane reported hearing a weak ELT signal in the area. Five witnesses were identified who either heard or saw the airplane just prior to the accident. One witness stated his attention was drawn to the airplane by the sound of trees snapping. This witness stated he did not hear the engine running prior to the airplane contacting the trees. The witness stated that one to two minutes after the airplane impacted the ground he heard a "poof" sound and observed flames coming from the airplane. He stated that it was not an explosion. Another witness reported seeing the airplane flying west at an altitude of about 200 feet above ground level (agl). This witness stated the engine was running rough. A third witness reported seeing the airplane flying at an altitude of 200 to 400 feet agl. This witness stated the engine was "sputtering" and then it stopped. A fourth witness, who was at his residence about 500 yards east of the accident site, stated he heard the airplane fly over his house. He stated the engine was very loud and that it "shook the house" as it flew overhead. This witness did not hear the impact, but did see smoke and flames coming from the field. A resident of a farm adjacent to the accident site stated he heard the airplane fly overhead and also heard it contact the trees. This witness stated the airplane's altitude was approximately twice the height of his barn when it flew overhead. He stated the engine was running slow. He stated he noticed a "black strip" by the door. PERSONNEL INFORMATION The pilot held an airline transport pilot certificate with a multi-engine land rating. The certificate contained commercial pilot privileges for single-engine land and single-engine sea airplane ratings. The pilot also held a flight instructor certificate with single-engine land, multi-engine land, and instrument airplane ratings. His instructor certificate was last renewed on November 2, 2003. The pilot held a third class medical issued on November 17, 2004. The medical certificate contained the limitation, "Holder shall wear lenses that correct for distant vision and possess glasses that correct for near vision. Not valid for any class after November 30, 2005." The pilot completed Phase VII of the FAA Pilot Proficiency Wings program on September 1, 2004. The last entry in the pilot's most recent logbook was dated December 16, 2004. According to the logbook, the pilot had a total flight time of 4,515.7 hours, of which 4,348.1 hours were logged as pilot-in-command. This logbook indicated the pilot had flown 643.3 hours in a Beech 35. The pilot's logbook indicated that he took possession of N5631K on August 30, 2003. Since that date, the pilot logged 205.4 hours in the airplane. AIRCRAFT INFORMATION N5631K was a low wing, V-tail, 1964-model Beech S35, serial number D-7389. According to FAA records, N5631K was registered to the pilot on December 13, 2003. According to the aircraft logbook, the last annual inspection on the airplane was completed on June 16, 2004, at a tachometer time of 957.8 hours and a total aircraft time of 5,496.5 hours. The last maintenance entry in the aircraft logbook was dated December 22, 2004. This entry listed the tachometer time of 1,076.5 hours. The tachometer reading at the time of the accident was 1,076.8 hours. The airplane was powered by a Teledyne Continental Motors IO-520-BA, serial number 280883-R. This remanufactured engine was installed in N5361K on October 9, 1993, at a tachometer time of 206.03 hours. On June 10, 1998, the cylinders were removed for a top overhaul. This occurred at a tachometer time of 696 hours which was 490 hours after the engine had been remanufactured. The last annual inspection of the engine was on June 16, 2004, at a tachometer time of 957.8 hours. At the time of this inspection the engine total time was listed as being 751.8 hours with a time since overhaul of 261.8 hours. The entry previous to the annual inspection was for an oil change on October 6, 2003, at a tachometer time of 884.0 hours. The mechanic who maintained the airplane stated the pilot routinely performed his own oil changes. He stated that in November 2004, the pilot informed him that there was fuel streaking down the left side of the fuselage. The mechanic stated that he inspected the airplane and did not find a fuel leak, but he did find a small oil leak. The mechanic stated that in December 2004, the fuel return line in the right wing split, so he replaced the lines in both of the wings. He stated he also changed the push rod tube seals on the number six cylinder since the seals were leaking. He stated he wanted to replace the remainder of the push rod seals along with some other work, but the pilot wanted to wait until he returned from flying the airplane to Florida and the Bahamas. The mechanic stated that on December 21 and 22, 2004, after the pilot returned from his trip, he replaced the sending unit gasket for the left tip tank. He stated he also installed an EZ oil sump heater. The mechanic stated that as he was inspecting the engine, he noticed the seventh stud on the number five cylinder was broken. The mechanic stated that this must have happened recently because it was not broken when he worked on the engine earlier in the month and he found the broken section of the stud in the bottom of the engine cowling. The mechanic stated he did not have the manuals or the tools to replace the stud, so they contacted an engine shop about doi ## Aircraft - Registration: [N5631K](https://openairdocs.org/deregistered/N5631K-2014-12-02), registration cancelled 2014-12-02, S/N D-7389, built 1964 (OpenAirDocs) - Reported make and model: Beech S35 - Registry model: [Beech S35](https://openairdocs.org/model/beech-s35) (registry code 1151532) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: D-7389 - Airframe hours: 5616 - Engines: Continental IO-520-BA6B 285 horsepower reciprocating - Damage: Substantial damage - Fire: On-Ground - Flight: Personal, Part 91 - Registered owner: Jacob R. Westerhof - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 1, 2004, 119 hours before - Departed: MTW, Manitowoc, WI - Destination: LOT, Romeoville, IL - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; injuries: fatal; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review September 1, 2004; seat: left; toxicology performed; flight hours: 4,516 total, 643 in this make and model, 4,348 as pilot in command, 66 in the last 90 days, 51 in the last 30 days, 34 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 5 knots - Visibility: 7 statute miles - Lowest ceiling: 6,000 ft overcast - Temperature: 16 °F, dew point 7 °F - Altimeter: 30.03 inHg - Observed at: SBM ## 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 20041225034409A](https://openairdocs.org/incident/20041225034409A), Dec 25, 2004: Beech S35, Sheboygan Falls, WI, Substantial damage, 2 fatal. (-23) Aircraft asked to be cleared for an approach into Sheboygan airport, sbm. A short time later, the pilot reported smoke in the cockpit and declared an… ## Docket (45 files) The files NTSB released with the investigation on October 12, 2005, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=60771. 24.2 MB in all. - Record of Interviews (item 1, .PDF, 112 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40410146&FileExtension=.PDF&FileName=Record%20of%20Interviews-Redacted.PDF - Air Traffic Control Information and Transcripts (item 2, .PDF, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40410147&FileExtension=.PDF&FileName=Air%20Traffic%20Control%20Information%20and%20Transcripts-Redacted.PDF - Sheboygan County Sheriff's Report (item 3, .PDF, 597 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239313&FileExtension=.PDF&FileName=Sheboygan%20County%20Sheriff%27s%20Report-Master.PDF - Engine Teardown Information (item 4, .PDF, 470 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239314&FileExtension=.PDF&FileName=Engine%20Teardown%20Information-Master.PDF - Teledyne Continental Motors Summary Report (item 5, .PDF, 158 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239315&FileExtension=.PDF&FileName=Teledyne%20Continental%20Motors%20Summary%20Report-Master.PDF - GPS Information (item 6, .PDF, 240 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239316&FileExtension=.PDF&FileName=GPS%20Information-Master.PDF - Contents in Sample Gasket Set (item 7, .PDF, 52 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239317&FileExtension=.PDF&FileName=Contents%20in%20Sample%20Gasket%20Set-Master.PDF - Letter From A & P Mechanic (item 8, .PDF, 70 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239318&FileExtension=.PDF&FileName=Letter%20From%20A%20%26%20P%20Mechanic-Master.PDF - Work Orders (item 9, .PDF, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40410148&FileExtension=.PDF&FileName=Work%20Orders-Redacted.PDF - Engine Logbook (item 10, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40410150&FileExtension=.PDF&FileName=Engine%20Logbook-Redacted.PDF - Toxicological Report (item 11, .PDF, 53 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40410151&FileExtension=.PDF&FileName=Toxicological%20Report-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 12, .PDF, 318 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40410152&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 13, .PDF, 69 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40410153&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.PDF - Photo 1. Aerial Photo of Accident Site and SBM (item 14, .PDF, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239350&FileExtension=.PDF&FileName=Photo%201.%20%20Aerial%20Photo%20of%20Accident%20Site%20and%20SBM-Master.PDF - Photo 2. Aerial Photo of Accident Site (item 15, .PDF, 253 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239359&FileExtension=.PDF&FileName=Photo%202.%20%20Aerial%20Photo%20of%20Accident%20Site-Master.PDF - Photo 3. Trees That Were Contacted (item 16, .PDF, 192 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239360&FileExtension=.PDF&FileName=Photo%203.%20%20Trees%20That%20Were%20Contacted-Master.PDF - Photo 4. Wreckage Path With Tree Branch in Foreground and Wreckage in Background. (TCM Photo) (item 17, .PDF, 191 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239361&FileExtension=.PDF&FileName=Photo%204.%20%20Wreckage%20Path%20With%20Tree%20Branch%20in%20Foreground%20and%20Wreckage%20in%20Background.%20(TCM%20Photo)-Master.PDF - Photo 5. Main Wreckage and Ground Impact Marks. (Sheboygan County Sheriff's Photo) (item 18, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239362&FileExtension=.PDF&FileName=Photo%205.%20%20Main%20Wreckage%20and%20Ground%20Impact%20Marks.%20(Sheboygan%20County%20Sheriff%27s%20Photo)-Master.PDF - Photo 6. Belly of Main Wreckage. (Sheboygan County Sheriff's Photo) (item 19, .PDF, 872 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239363&FileExtension=.PDF&FileName=Photo%206.%20%20Belly%20of%20Main%20Wreckage.%20%20(Sheboygan%20County%20Sheriff%27s%20Photo)-Master.PDF - Photo 7. Ground Impact With Pieces of Windshield (item 20, .PDF, 212 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239365&FileExtension=.PDF&FileName=Photo%207.%20%20Ground%20Impact%20With%20Pieces%20of%20Windshield-Master.PDF - Photo 8. Front View of Wreckage (item 21, .PDF, 215 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239367&FileExtension=.PDF&FileName=Photo%208.%20%20Front%20View%20of%20Wreckage-Master.PDF - Photo 9. Right Side View of Wreckage (item 22, .PDF, 208 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239368&FileExtension=.PDF&FileName=Photo%209.%20%20Right%20Side%20View%20of%20Wreckage-Master.PDF - Photo 10. Left Rear View of Wreckage (item 23, .PDF, 196 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239369&FileExtension=.PDF&FileName=Photo%2010.%20%20Left%20Rear%20View%20of%20Wreckage-Master.PDF - Photo 11. Engine and Propeller (item 24, .PDF, 215 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239371&FileExtension=.PDF&FileName=Photo%2011.%20%20Engine%20and%20Propeller-Master.PDF - Photo 12. Door (item 25, .PDF, 204 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239373&FileExtension=.PDF&FileName=Photo%2012.%20%20Door-Master.PDF - Photo 13. Oil Streak Down the Side of the Wreckage (item 26, .PDF, 160 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239375&FileExtension=.PDF&FileName=Photo%2013.%20%20Oil%20Streak%20Down%20the%20Side%20of%20the%20Wreckage-Master.PDF - Photo 14. Holes in Top of Crankcase (item 27, .PDF, 203 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239378&FileExtension=.PDF&FileName=Photo%2014.%20%20Holes%20in%20Top%20of%20Crankcase-Master.PDF - Photo 15. Oil Sump (TCM Photo) (item 28, .PDF, 446 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239379&FileExtension=.PDF&FileName=Photo%2015.%20%20Oil%20Sump%20(TCM%20Photo)-Master.PDF - Photo 16. Accessory Section (TCM Photo) (item 29, .PDF, 442 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239380&FileExtension=.PDF&FileName=Photo%2016.%20%20Accessory%20Section%20(TCM%20Photo)-Master.PDF - Photo 17. Fractured 7th Stud on the Number 5 Cylinder. (TCM Photo) (item 30, .PDF, 385 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239381&FileExtension=.PDF&FileName=Photo%2017.%20%20Fractured%207th%20Stud%20on%20the%20Number%205%20Cylinder.%20(TCM%20Photo)-Master.PDF - Photo 18. Inside of Crankcase (TCM Photo) (item 31, .PDF, 448 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239382&FileExtension=.PDF&FileName=Photo%2018.%20%20Inside%20of%20Crankcase%20(TCM%20Photo)-Master.PDF - Photo 19. Inside of Crankcase (TCM Photo) (item 32, .PDF, 438 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239383&FileExtension=.PDF&FileName=Photo%2019.%20%20Inside%20of%20Crankcase%20(TCM%20Photo)-Master.PDF - Photo 20. Crankcase and Connecting Rods (TCM Photo) (item 33, .PDF, 444 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239384&FileExtension=.PDF&FileName=Photo%2020.%20%20Crankcase%20and%20Connecting%20Rods%20(TCM%20Photo)-Master.PDF - Photo 21. Number 4 Connecting Rod Journal (TCM Photo) (item 34, .PDF, 444 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239385&FileExtension=.PDF&FileName=Photo%2021.%20Number%204%20Connecting%20Rod%20Journal%20(TCM%20Photo)-Master.PDF - Photo 22. Bearings (TCM Photo) (item 35, .PDF, 433 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239386&FileExtension=.PDF&FileName=Photo%2022.%20%20Bearings%20(TCM%20Photo)-Master.PDF - Photo 23. Numbers 1, 3, and 6 Cylinders and Pistons (TCM Photo) (item 36, .PDF, 453 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239388&FileExtension=.PDF&FileName=Photo%2023.%20%20Numbers%201,%203,%20and%206%20Cylinders%20and%20Pistons%20(TCM%20Photo)-Master.PDF - Photo 24. Cylinder Base Packing On the Number 4 Cylinder (TCM Photo) (item 37, .PDF, 401 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239392&FileExtension=.PDF&FileName=Photo%2024.%20%20Cylinder%20Base%20Packing%20On%20the%20Number%204%20Cylinder%20(TCM%20Photo)-Master.PDF - Photo 25. Bottom of Number 3 Piston (TCM Photo) (item 38, .PDF, 429 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239394&FileExtension=.PDF&FileName=Photo%2025.%20%20Bottom%20of%20Number%203%20Piston%20(TCM%20Photo)-Master.PDF - Photo 26. Bottom of Number 5 Piston (TCM Photo) (item 39, .PDF, 444 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239396&FileExtension=.PDF&FileName=Photo%2026.%20%20Bottom%20of%20Number%205%20Piston%20(TCM%20Photo)-Master.PDF - Photo 27. Number 4 Cylinder (TCM Photo) (item 40, .PDF, 379 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239397&FileExtension=.PDF&FileName=Photo%2027.%20%20Number%204%20Cylinder%20(TCM%20Photo)-Master.PDF - Photo 28. Bottom of Number 4 Piston (TCM Photo) (item 41, .PDF, 450 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239398&FileExtension=.PDF&FileName=Photo%2028.%20%20Bottom%20of%20Number%204%20Piston%20(TCM%20Photo)-Master.PDF - Photo 29. Bottom of Number 6 Piston (TCM Photo ) (item 42, .PDF, 448 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239400&FileExtension=.PDF&FileName=Photo%2029.%20%20Bottom%20of%20Number%206%20Piston%20(TCM%20Photo%20)-Master.PDF - Photo 30. Cylinder Base Packing Removed From Engine and New Base Packing For IO-520 Engines (TCM Photo) (item 43, .PDF, 388 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239401&FileExtension=.PDF&FileName=Photo%2030.%20%20Cylinder%20Base%20Packing%20Removed%20From%20Engine%20and%20New%20Base%20Packing%20For%20IO-520%20Engines%20(TCM%20Photo)-Master.PDF - Photo 31. Cylinder Base Packing Removed From Engine and New Base Packing For IO-520 Engines (TCM Photo) (item 44, .PDF, 415 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239403&FileExtension=.PDF&FileName=Photo%2031.%20%20Cylinder%20Base%20Packing%20Removed%20From%20Engine%20and%20New%20Base%20Packing%20For%20IO-520%20Engines%20(TCM%20Photo)-Master.PDF - Photo 32. Cylinder Base Packing for an O-470 Compared to the Cylinder Base Packing for an IO-520 (TCM Photo) (item 45, .PDF, 389 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40239406&FileExtension=.PDF&FileName=Photo%2032.%20%20Cylinder%20Base%20Packing%20for%20an%20O-470%20Compared%20to%20the%20Cylinder%20Base%20Packing%20for%20an%20IO-520%20(TCM%20Photo)-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.