The U.S. aircraft register, updated daily
Parts · Airframe structure

Unknown

28,313 failure reports named the unknown in the last ten years, 36,110 since 1998, most often on the Boeing 737; the condition most often found was "unknown". 49 FAA approvals let 25 companies make a replacement unknown, Air Cruisers holding the most (12).

Reports by year

04,6479,29413,94218,5891998200420092014201920247572026
Reports by year, as a table
reports
19989
199944
2000180
200178
20031
200426
200563
2006456
20071,073
2008551
2009487
2010691
20111,147
2012797
2013881
2014694
2015619
2016561
2017832
20181,026
20191,339
2020651
2021824
2022789
202318,589
20241,885
20251,060
2026757

Which system the reports file it under last ten years

Airframe structure12,045Heating, ice protection and utility systems8,030Electrical power2,049Engine1,683Instruments and avionics1,389Flight controls995Cabin, seats and restraints759Landing gear611Fuel system362Emergency equipment359
Reports by system, as a table
reports
Airframe structure12,045
Heating, ice protection and utility systems8,030
Electrical power2,049
Engine1,683
Instruments and avionics1,389
Flight controls995
Cabin, seats and restraints759
Landing gear611
Fuel system362
Emergency equipment359

Models most often reporting it last ten years

Boeing 7375,859Airbus A3203,496Boeing 7572,568Boeing 7672,553Bombardier CL-600 Challenger and CRJ1,902Airbus A3191,701Airbus A3301,602Airbus A3211,470Embraer EMB-145 ERJ 1451,171Boeing 7171,157Embraer ERJ 170 E170 and E175745Boeing 747429
Models most reported, as a table
reports
Boeing 7375,859
Airbus A3203,496
Boeing 7572,568
Boeing 7672,553
Bombardier CL-600 Challenger and CRJ1,902
Airbus A3191,701
Airbus A3301,602
Airbus A3211,470
Embraer EMB-145 ERJ 1451,171
Boeing 7171,157
Embraer ERJ 170 E170 and E175745
Boeing 747429

How it failed the condition found, last ten years

unknown18,813odor5,173malfunctioned1,347corroded764cracked384smoke359fumes183damaged151vibration118gouged114
Conditions found, as a table
reports
unknown18,813
odor5,173
malfunctioned1,347
corroded764
cracked384
smoke359
fumes183
damaged151
vibration118
gouged114

Engines most often reporting it

Rolls-Royce RB-211 series 69General Electric CF6-80C2B6 66International Aero Engines PW1133GA-JM 52Allison (Rolls-Royce) 250-C47B 31Pratt & Whitney PW4062 27CFM International CFM56-7B27 22CFM International CFM56-7B27E 22CFM International LEAP-1B28 series 21Turbomeca (Safran) ARRIEL 2B1 21Pratt & Whitney PW4060 19

Approved replacement parts 49 parts manufacturer approvals

A parts manufacturer approval (PMA) lets a company other than the aircraft's maker make a unknown and sell it as an approved part for the models named. These are the companies holding such approvals for a unknown:

Air Cruisers 12Jet Parts Engineering INC 7Aero Products INC 4Exotic Metals Forming Company 3Mcfarlane Aviation INC 2Keystone Helicopter Corporation 2Vickers INC, Electromech Division 1United Ring and Seal INC 1Ta Manufacturing 1Simmonds Precision, Bf Goodrich 1Simmonds Precision Products INC Goodrich Sensors and Integrated Systems - Vt 1Safe Air Repair INC 1Ozone Industries INC 1Litton Electron Devices 1Imo Industries INC, Controlex Div 1Hughes Network Systems 1Hughes Avicom Intn'L 1Honeywell International US LLC 1Honeywell International INC, Controls and Accessories 1Honeywell International INC 1Harco Laboratories INC 1Hamilton Sundstrand Corporation 1Growth Industries INC 1Cook Airtomic 1Causey Aviation Svc INC 1

For these models most: Boeing 757 (7), Bell 222 (6), Bell 206 JetRanger and LongRanger (5), Boeing 747 (4), Mcdonnell Douglas DC-9 (3), Boeing 767 (3), Bell 412 (3), Piper PA-32 Cherokee Six, Lance and Saratoga (2), Piper PA-28 Cherokee, Warrior, Archer and Arrow (2), Bell 214 (2), Swearingen SA227 (1), Sikorsky S-76 (1).

MakerPartReplacesFitsGrantedStatus
Jet Parts Engineering INCUnknown 3170334JP-13170334-1Boeing 757-200, -3002003-08-05current
Jet Parts Engineering INCUnknown 3170344JP-23170344-2Boeing 757-200, -3002003-08-05current
Jet Parts Engineering INCUnknown 3170335JP-13170335-1Boeing 757-200, -3002003-08-05current
Jet Parts Engineering INCUnknown 358038JP-8358038-8Boeing 757-200, -3002003-08-05current
Jet Parts Engineering INCUnknown 974386JP-6974386-6Boeing 757-200, -3002003-08-05current
Jet Parts Engineering INCUnknown 974184JP-2974184-2Boeing 757-200, -3002003-08-05current
Jet Parts Engineering INCUnknown 858457JP-4858457-4Boeing 757-200, -3002003-08-05current
Growth Industries INCUnknown 2958490-1GMcDonnell Douglas 2958490-1Boeing 717 Series, DC9, MD882003-07-07current
Harco Laboratories INCUnknown 18725799787Pratt & Whitney P&W has design propriety rights to this part.2002-09-02current
Exotic Metals Forming CompanyUnknown 10190-600Boeing BACF22AM600Boeing 747-100, -200, -3002000-10-23current
Exotic Metals Forming CompanyUnknown 10180-800Boeing BACF22AN800Boeing 747-100, -200, -3002000-10-23current
Exotic Metals Forming CompanyUnknown 10317-500Boeing BACF22BD500ABoeing 747-100, -200, -3002000-10-23current
Simmonds Precision, Bf GoodrichUnknown DL5040M8N/AFairchild Aircraft SA226-T, SA226-AT, SA226-T(B)1999-03-28current
Vickers INC, Electromech DivisionUnknown D1845-410-61339-4Boeing 7371998-11-05current
Ta ManufacturingUnknown BACC10CC12CBoeing BACC10CC12CBoeing 707-100, 707-200, 707-3001998-08-04current
Honeywell International INC, Controls and AccessoriesUnknown 4243811-2Harness J2 ExtensionLearjet 31, 31A1998-03-29current
Simmonds Precision Products INC Goodrich Sensors and Integrated Systems - VtUnknown 30042-0000-0501No unique Airbus part numberAirbus A321-111, -112, -1311997-09-14current
Litton Electron DevicesUnknown All Litton parts listed in...See attached Dwg. No. PA-4023Miscellaneous See attached Dwg. No. PA-4023, Rev....1997-07-15current
Ozone Industries INCUnknown OMP4281-8SAAB 9303592-006Saab Aircraft AB SAAB 20001997-03-30current
Cook AirtomicUnknown AIR18320-9General Electric CF6-80A when Hamilton Standard High...1997-01-16current
Aero Accessories INCUnknown AA211CWAirborne 211CWTextron Lycoming LIO-360, GO-435, TIO-5411996-10-17current
Avglas Manufacturing COUnknown 530852, and 531143Modification PartTeledyne Continental O-3001996-07-16current
Keystone Helicopter CorporationUnknown All parts listed in...Sikorsky S-76A, B, C1996-01-29current
A & B Plastic INCUnknown 403The Boeing Co 1522-151Boeing 727-100, -2001995-10-09current
Honeywell International INCUnknown 122944-1-1McDonnell Douglas 122944-1-1McDonnell Douglas DC-9-11, -12, -131995-08-29current
Mcfarlane Aviation INCUnknown Dwg List 1117Piper 69791-000Piper PA-28R-200 S/N's 28-35001 & on,...1995-06-18current
Mcfarlane Aviation INCUnknown UnknownPiper 69790-00Piper PA-28R-201, PA-28RT-201, PA-32-2601995-06-18current
Hughes Network SystemsUnknown 1015990-0001Hughes/Claircom 1015990-0001Aerospatiale ATR721995-04-16current
Hamilton Sundstrand CorporationUnknown SD1318Modification PartAirbus A300-B2-1A, B2-1C, B2-2031995-03-26current
Keystone Helicopter CorporationUnknown Dwg MDL87-11Bell 4121994-08-21current
Honeywell International US LLCUnknown Report R01-52Modification PartLockheed 1329-23A, D, E1994-02-07current
Safe Air Repair INCUnknown Dwg List SAR-100Any American Champion part with the same part...Miscellaneous Refer to Dwg List SAR-1001993-12-28current
Hughes Avicom Intn'LUnknown Parts listed on Audio Tape...Modification PartMcDonnell Douglas DC-9-82 (MD-82)1993-09-20current
Imo Industries INC, Controlex DivUnknown 411-B-0317Douglas 7-42767-1McDonnell Douglas DC-10-10, -40, -301993-08-29current
Aero Products INCUnknown HAI-LDG-031-100Modification PartsBell 2221993-01-26current
Aero Products INCUnknown HAI-SW-170-447Modification PartsBell 2221993-01-26current
Aero Products INCUnknown Dwg No. HAI-LDG-031-100Modification PartBell 2221993-01-19current
Aero Products INCUnknown Dwg HAI-SW-170-447Modification Parts)Bell 2221993-01-19current
Causey Aviation Svc INCUnknown CA62834-80262834-802Piper All PA-28-151, -151, -1811991-12-04current
United Ring and Seal INCUnknown URS 238446PWA 238446Pratt & Whitney Wasp Jr. B3, B4, B51991-10-24current
Air CruisersUnknown D24541-()Bell 206-050-168Bell Helicopter Textron 206L1991-08-14current
Air CruisersUnknown D24501-( )Bell 206-050-168Bell 206B1991-08-14current
Air CruisersUnknown D34059-()Bell 214-052-200Bell 214ST1991-06-16current
Air CruisersUnknown D24922-()Bell 412-947-013Bell 4121991-06-16current
Air CruisersUnknown D24974-()Bell 206-050-248Bell 206B, L1991-06-16current
Air CruisersUnknown 20D24391-()Bell 205-050-110Bell 205A1991-06-16current
Air CruisersUnknown 24976-()Bell 206-050-248Bell 206B, L1991-06-16current
Air CruisersUnknown D34038-()Bell 214-052-200Bell 214ST1991-06-16current
Air CruisersUnknown D24921-()Bell 412-947-013Bell 4121991-06-16current
Air CruisersUnknown D24727-()Bell 222-336-101Bell 2221991-06-16current
Air CruisersUnknown D24972-()Bell 206-050-248Bell 206B, L1991-06-16current
Air CruisersUnknown D24728-()Bell 222-336-101Bell 2221991-06-16current

Sources: the FAA's service difficulty reports since 1995 (a report is a part that failed and was fixed, as filed by an airline, repair station or owner; the count shows reporting as much as reliability) and the parts manufacturer approvals in the FAA's Dynamic Regulatory System. The part name is the reporters' and the approval holders' own words, reduced to the first plain words so that spellings meet.