# NTSB MIA99FA005: Boeing 727-224, N66734, Miami, FL, October 7, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Field investigation · Final report - Date: October 7, 1998, 07:09 local (11:09 UTC) - Place: Miami, FL - Location: 25.7954° N, 80.2901° W: Placed by OpenAirDocs at MIAMI INTL (MIA), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=25.7954&lon=-80.2901&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 81 uninjured - Status: Completed, report September 12, 2000 - Report: Approved by Office Director - Safety recommendations: Yes - NTSB case key (mKey): 44108 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA99FA005 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/44108/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=44108 - Page: https://openairdocs.org/ntsb/MIA99FA005 ## Probable cause The catastrophic failure of the 8th stage high pressure compressor disk from cadmium embrittlement as a result of improper adherence to the prescribed plating procedures and requirements by the company that last plated the disk. Contributing to the accident was the failure of the engine repair company to provide adequate surveillance and oversight of the plating company, the engine repair companies use of an unauthorized repair vendor, the plating company, and the engine repair companies failure to inform the aircraft operator that they had used the plating company which was not on the aircraft operators vendor list. Also contributing to the accident was the aircraft operators failure to audit the engine repair company to the level of detail that they would have discovered the engine repair company was using an unauthorized repair vendor. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, takeoff - roll/run - maintenance,overhaul,major - improper, other maintenance personnel (cause) - improper use of procedure, other maintenance personnel (cause) - inadequate surveillance of operation, other institution (cause) - compressor assembly,rotor disc - brittle fracture - compressor assembly,rotor disc - failure,total ## Analysis During the initial part of the takeoff, prior to the engines reaching takeoff power, the No. 2 engine had an uncontained failure of the 8th stage HPC disk. The takeoff was aborted, the passengers were bussed to the terminal, and the aircraft was towed to the gate. Metallurgical examination of the 8th stage HPC disk showed that a significant amount of cadmium was present on steel base metal in the area of the fracture surfaces and the surface had an inadequate nickel coating. The disk had accumulated 359 flight hours since overhaul. The disk had been nickel-cadmium plated in March 1996 and was stored until February 1998, when it was installed in the accident engine during repair. Other HPC disk installed in the accident engine, which had been nickel-cadmium plated by the same company as the 8th stage HPC disk, were also found to have inadequate nickel coating. During nickel-cadmium plating the nickel acts as a barrier coating between the cadmium and the steel part to prevent cadmium from contacting the steel part, which can cause cadmium embrittlement. ## Factual narrative HISTORY OF FLIGHT On October 7, 1998, about 0709 eastern daylight time, a Boeing 727-224, N66734, registered to First Security Bank NA, and operated by Continental Airlines, Inc., as flight 1521, Title 14 CFR Part 121 scheduled domestic passenger service from Miami, Florida, to Houston, Texas, had an uncontained failure of the No. 2 engine during takeoff roll at Miami. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The aircraft received substantial damage. The airline transport-rated captain, first officer, flight engineer, 3 flight attendants, and 75 passengers were not injured. The flight was originating at the time of the accident. The captain stated he was flying the aircraft and advanced the engine power levers for takeoff. The engines spooled up, and just prior to maximum takeoff power being set, he heard a loud bang noise. He retarded the power levers and aborted the takeoff. He turned off the runway at the next taxiway. The No. 2 engine was identified as having failed and the engine shutdown procedure was accomplished and the fire handle was pulled. The fire bottles were then fired. He made contact with the fire department personnel who arrived shortly after the aborted takeoff and they reported there was no fire. A portable airstair was brought to the aircraft and the crew and passengers deplaned and were taken to the terminal building by bus. PERSONNEL INFORMATION Information on the flightcrew is contained in this report under First Pilot Information and in the Pilot/Operator Aircraft Accident Report. AIRCRAFT INFORMATION The No. 2 engine was a Pratt and Whitney model JT8D-9A, serial number 657091. At the time of the accident the engine had accumulated 68,784 total flight hours and 57,530 total cycles. The engine had accumulated 4,846 flight hours since overhaul and 359 flight hours since repair. On March 2, 1998, 359 flight hours before failure, the No. 2 engine was repaired by General Electric Engine Services, Miami, Florida. The N1 and N2 compressors, hot section, N2 turbine and exhaust case were repaired under heavy maintenance criteria. The N1 turbine and main accessory gearbox were repaired under heavy repair criteria. Installed were the C-5, C-6, C-8, C-9, and C-10 disks. The C-8 or 8th stage high pressure compressor (HPC) disk, which was installed at this time, had been overhauled by General Electric Engine Services (formerly Greenwich Air Services), Miami, Florida, on February 11, 1998. Records showed the disk was received by Greenwich Air Services in March 1996. The disk was sent to Action Plating Corporation, Opa-Locka, Florida, for stripping. The disk was then returned to Greenwich Air Services, where it was inspected. The disk was then sent by Greenwich Air Services to Wings Aviation Services, Miami, Florida, for plating with diffused nickel-cadmium. The disk was then stored until February 1998. (Additional aircraft information is contained in this report under Aircraft Information and in the Powerplants Group Chairman Factual Report). METEOROLOGICAL INFORMATION Visual meteorological conditions prevailed at the time of the accident. Additional meteorological information is contained in this report under Weather Information. FLIGHT RECORDERS The cockpit voice recorder from N66734 was not retained by NTSB, for it remained electrically powered after the accident and the event was over written. The digital flight data recorder from N66734 was retained by NTSB after the accident and forwarded to the NTSB Vehicle Reorders Division, Washington, D.C., for readout. The readout showed the aircraft aligned with the takeoff runway and engine power was advanced. The engine pressure ratios increased to 1.44, 1.51, and 1.46, on engines 1, 2, and 3 respectively. The recording on the digital flight data recorder then ends. (See Flight Data Recorder Specialist's Factual Report of Investigation). WRECKAGE AND IMPACT INFORMATION Examination of the aircraft after the accident showed the No. 2 engine had experienced an uncontained failure of the 8th stage HPC disk. The two forward pieces of the No. 2 engine cowling separated and were found on the runway. Damage to the vertical tail had occurred from ejected engine components. Pieces from the 8th stage HPC disk were located inside the vertical tail of the aircraft, about 500 feet to the right of the aircraft, and about 500 feet to the left of the aircraft. (Additional Wreckage and Impact information is contained in the Powerplants Group Chairman Factual Report) MEDICAL AND PATHOLOGICAL INFORMATION There were no reported injuries from the three flightcrew members, 3 flight attendants, and 75 passengers. The flightcrew members did not submit to toxicology testing after the accident. TESTS AND RESEARCH Metallurgical examination of the 8th stage HPC hub fracture surfaces revealed the presence of a crack extending inboard from the rim radius, intersecting a shielding hole, and continuing partially into the bore. Elemental analysis of the fracture surface revealed a significant amount of cadmium in contact with the steel base material. The hub was nickel-cadmium (NiCd) plated during its last overhaul in March-April 1996, by Wings Aviation Services Inc. (Wings) in Miami. The NiCd plating operation requires applying a base layer of nickel followed by a top layer of cadmium and then baking to diffuse the two elements together. The nickel acts as a barrier coating between the cadmium and the base material (steel) to prevent the cadmium from contacting the steel base material, which may cause cadmium embrittlement. The remaining Wings plated HPC disks from the accident engine were metallurgically examined and found to have inadequate Ni coating. The Federal Aviation Administration (FAA) issued an Airworthiness Directive (AD) to require the removal of JT8D and JT3D HPC disk that had been NiCd plated by Wings based on the number of hours in service that the disk had accumulated since being NiCd plated. (See Powerplants Group Chairman Factual Report and NTSB Materials Laboratory Factual Report). ADDITIONAL INFORMATION The aircraft was released by NTSB to Guy Puglia, Senior Manager Propulsion Engineering, Continental Airlines, Inc., on October 10, 1998. The No. 2 engine and accessories, and the digital flight data recorder, which were retained by NTSB, were released by NTSB to Eugene A. Carroll, Director Safety Investigations, Continental Airlines, Inc., on December 16, 1998. Additional parties to the NTSB investigation were: Avi Swartzon Wings Aviation Services, Inc. Miami, Florida William F. Bain Action Plating Corporation Opa-Locka, Florida Mike Careccia Independent Association of Continental Pilots Houston, Texas John Martens General Electric Engines Services Cincinnati, Ohio Additional NTSB personnel assigned to this investigation were: Jean-Pierre Scarfo-Powerplants Group Chairman Jean Bernstein-Metallurgist David Case- Flight Data Recorder Jeffrey Guzzetti-Powerplants George Anderson-Powerplants Debbie Bruce-Powerplants ## Aircraft - Registration: [N66734](https://openairdocs.org/deregistered/N66734-2008-08-11), registration cancelled 2008-08-11, S/N 20663, built 1974 (OpenAirDocs) - Reported make and model: Boeing 727-224 - Registry model: [Boeing 727-224](https://openairdocs.org/model/boeing-727-224) (registry code 1384076) (OpenAirDocs) - Registry engine: [Pratt & Whitney JT8D-5](https://openairdocs.org/engine/pratt-whitney-jt8d-5) (registry code 52046, turbo-jet) (OpenAirDocs) - Category: Airplane - Serial number: 20663 - Airframe hours: 3503 - Engines: P&W JT8D-9A 14500 lbs thrust turbo fan - Damage: Substantial damage - Fire: On-Ground - Flight: Part 121 - Operator: Continental Airlines, Inc. - Registered owner: First Security Bank Na Trustee - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, September 1, 1998, 312 hours before - Departed: MIA - Destination: IAH, HOUSTON, TX - Flight plan: IFR - Airport: MIA, Miami International, runway 9L, 10,502 × 200 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 14,900 total, 4,500 in this make and model, 7,500 as pilot in command, 226 in the last 90 days, 53 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 75 °F - Altimeter: 30.00 inHg - Observed at: MIA, 1 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 19981007035229A](https://openairdocs.org/incident/19981007035229A), Oct 7, 1998: Boeing 727224, Miami, FL, Substantial damage. On October 7, 1998, about 0710 eastern daylight time, a Boeing 727-224, N66734, operated by Continental airlines, inc. as flight 1521, title 14 CFR part 121… ## Docket (22 files) The files NTSB released with the investigation on March 25, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=44108. 18.9 MB in all. - Supplement s (item 1, PDF, 1 page, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13488748&FileExtension=pdf&FileName=Supplement%20S-Master-Rel.pdf - Powerplants 8-factual report of group chairman (item 2, PDF, 140 pages, 10.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13488751&FileExtension=pdf&FileName=Powerplants%208-Factual%20Report%20of%20Group%20Chairman-Master-Rel.pdf - Materials laboratory 15-factual report of group chairman (item 3, PDF, 11 pages, 436 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13521981&FileExtension=pdf&FileName=Materials%20Laboratory%2015-Factual%20Report%20of%20Group%20Chairman-Master-Rel.pdf - Materials laboratory 15-factual report of group chairman-4 (item 4, PDF, 6 pages, 218 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13521892&FileExtension=pdf&FileName=Materials%20Laboratory%2015-Factual%20Report%20of%20Group%20Chairman-4-Master-Rel.pdf - Flight data recorder 10-factual report of group chairman (item 5, PDF, 15 pages, 520 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13521977&FileExtension=pdf&FileName=Flight%20Data%20Recorder%2010-Factual%20Report%20of%20Group%20Chairman-Master-Rel.pdf - Pilot-operator aircraft accident report NTSB form 61201-2 (item 6, PDF, 15 pages, 969 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13521646&FileExtension=pdf&FileName=Pilot-Operator%20Aircraft%20Accident%20Report%20NTSB%20Form%2061201-2-Master-Rel.pdf - Transcript of radio communications (item 7, PDF, 17 pages, 379 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13527157&FileExtension=pdf&FileName=Transcript%20of%20Radio%20Communications-Master-Rel.pdf - Reports from federal agencies_ATC controller statements (item 8, PDF, 4 pages, 344 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13514002&FileExtension=pdf&FileName=Reports%20from%20Federal%20Agencies_ATC%20Controller%20Statements-Master-Rel.pdf - Other pertinent forms and reports_aircraft maitenance records (item 9, PDF, 17 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13516688&FileExtension=pdf&FileName=Other%20Pertinent%20Forms%20and%20Reports_Aircraft%20Maitenance%20Records-Master-Rel.pdf - Other pertinent forms and reports_FAA airworthiness directive 99-01-08 (item 10, PDF, 11 pages, 717 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13516684&FileExtension=pdf&FileName=Other%20Pertinent%20Forms%20and%20Reports_FAA%20Airworthiness%20Directive%2099-01-08-Master-Rel.pdf - Statement of party representatives to NTSB investigation (item 11, PDF, 6 pages, 730 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13500420&FileExtension=pdf&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master-Rel.pdf - Release of aircraft wreckage NTSB form 612015 (item 12, PDF, 2 pages, 115 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13513770&FileExtension=pdf&FileName=Release%20of%20Aircraft%20Wreckage%20%20NTSB%20Form%20612015-Master-Rel.pdf - Reports from parties to the investigation_submission from wings aviation services inc (item 13, PDF, 32 pages, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13499942&FileExtension=pdf&FileName=Reports%20from%20Parties%20to%20the%20Investigation_Submission%20from%20Wings%20Aviation%20Services%20Inc-Master-Rel.pdf - Powerplants factual report photo 1_left side view of installed engine showing exit wounds no negative (item 14, PDF, 1 page, 33 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13499387&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%201_Left%20side%20view%20of%20installed%20engine%20showing%20exit%20wounds%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 2_left side showing tear in vertical stabilizer no negative (item 15, PDF, 1 page, 26 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13513853&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%202_Left%20side%20showing%20tear%20in%20vertical%20stabilizer%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 3_detailed view of vertical stabilizer damage no negative (item 16, PDF, 1 page, 23 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13499938&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%203_Detailed%20view%20of%20vertical%20stabilizer%20damage%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 4_a segment of the 8th stage disk found in the vertical stabilizer no negative (item 17, PDF, 1 page, 26 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13499383&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%204_A%20segment%20of%20the%208th%20stage%20disk%20found%20in%20the%20vertical%20stabilizer%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 5_fan-discharge rear outer duct peeled back no negative (item 18, PDF, 1 page, 22 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13499379&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%205_Fan-discharge%20rear%20outer%20duct%20peeled%20back%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 6_recovered pieces of the 8TH-stage disk no negative (item 19, PDF, 1 page, 28 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13499355&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%206_Recovered%20pieces%20of%20the%208th-stage%20disk%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 7_8TH-stage disk with the fan discharge rear outer duct peeled back no negative (item 20, PDF, 1 page, 25 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13500416&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%207_8th-stage%20disk%20with%20the%20fan%20discharge%20rear%20outer%20duct%20peeled%20back%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 8_8TH-stage disk area fractures no negative (item 21, PDF, 1 page, 24 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13513849&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%208_8th-stage%20disk%20area%20fractures%20No%20negative-Master-Rel.pdf - Powerplants factual report photo 9_7TH-AND 8TH-stage stator damage no negative (item 22, PDF, 1 page, 35 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13499934&FileExtension=pdf&FileName=Powerplants%20Factual%20Report%20Photo%209_7th-and%208th-stage%20stator%20damage%20No%20negative-Master-Rel.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.