Heating, ice protection and utility systems
Heating and cooling, cabin pressure, protection against ice and rain, and the hydraulic, pneumatic and vacuum systems that power other equipment.
Operators and repair shops have filed 85,830 failure reports about this system since 1995, 31,595 of them in the last ten years. The FAA has issued 305 airworthiness directives on it, the most recent October 26, 2026. The part most often named in the reports is the a/c pack. Among model families, the Boeing 737 appears most often in the last ten years; taking fleet size into account, the Boeing 767 has the highest rate among sizeable fleets, about 79.3 reports a year for every 100 aircraft.
Failure reports by year as filed with the FAA
Failure reports by year, as a table
| reports | |
|---|---|
| 95 | 1,654 |
| 96 | 2,048 |
| 97 | 2,230 |
| 98 | 2,060 |
| 99 | 2,060 |
| 00 | 2,172 |
| 01 | 2,387 |
| 02 | 2,158 |
| 03 | 1,984 |
| 04 | 1,993 |
| 05 | 2,135 |
| 06 | 2,283 |
| 07 | 2,546 |
| 08 | 2,375 |
| 09 | 2,463 |
| 10 | 2,853 |
| 11 | 3,643 |
| 12 | 3,121 |
| 13 | 3,745 |
| 14 | 2,782 |
| 15 | 2,738 |
| 16 | 2,805 |
| 17 | 3,376 |
| 18 | 3,825 |
| 19 | 4,165 |
| 20 | 2,437 |
| 21 | 2,883 |
| 22 | 2,997 |
| 23 | 3,514 |
| 24 | 2,947 |
| 25 | 3,107 |
| 26 | 2,344 |
Models most often named last ten years
Boeing 7378,410Boeing 7674,640Airbus A3204,354Airbus A3212,250Airbus A3191,762Bombardier CL-600 Challenger and CRJ1,741Embraer EMB-145 ERJ 1451,615Boeing 7571,201Airbus A330711Embraer ERJ 170 E170 and E175601Boeing 777497Airbus A300367
Model families most named, as a table
Highest rate, fleets of 500 or more reports a year per 100 aircraft registered
Boeing 767 79.3Airbus A320 54.8Boeing 737 29.1Airbus A321 24.1Bombardier CL-600 Challenger and CRJ 10.5Embraer ERJ 170 E170 and E175 7.9Cessna 680 Citation Sovereign and Latitude 3.7Bombardier BD-100 Challenger 300 and 350 2.9Embraer EMB-505 Phenom 300 2.4Cessna 560 Citation V, Ultra, Encore and Excel 1.8
Parts most often named
A/C Pack1,419Controller1,337Warning Light1,109Warning Message1,041Fan1,011Pump948Warning System931Valve910Acm804Control Valve791Filter734Sensor599
Parts most reported, as a table
| reports | |
|---|---|
| A/C Pack | 1,419 |
| Controller | 1,337 |
| Warning Light | 1,109 |
| Warning Message | 1,041 |
| Fan | 1,011 |
| Pump | 948 |
| Warning System | 931 |
| Valve | 910 |
| Acm | 804 |
| Control Valve | 791 |
| Filter | 734 |
| Sensor | 599 |
Who made the parts named last ten years, as the reports code them
Honeywell International INC (Engine)366The Boeing CO342Hamilton Sunstrand CORP340Group Economique Airbus Industrie312Eaton CORP262Honeywell INC201Nord Aviation SA133Cessna Aircraft CORP104Parker Hannifin (Incl Clev Whl & Bk)104Technofan99
Part makers most named, as a table
| reports | |
|---|---|
| Honeywell International INC (Engine) | 366 |
| The Boeing CO | 342 |
| Hamilton Sunstrand CORP | 340 |
| Group Economique Airbus Industrie | 312 |
| Eaton CORP | 262 |
| Honeywell INC | 201 |
| Nord Aviation SA | 133 |
| Cessna Aircraft CORP | 104 |
| Parker Hannifin (Incl Clev Whl & Bk) | 104 |
| Technofan | 99 |
What was wrong with them the condition reported
Odor7,021Failed4,010False Activation2,651Leaking2,048Malfunctioned2,011Faulted1,793Faulty1,402Inoperative1,214Damaged737Contaminated589
Conditions most reported, as a table
| reports | |
|---|---|
| Odor | 7,021 |
| Failed | 4,010 |
| False Activation | 2,651 |
| Leaking | 2,048 |
| Malfunctioned | 2,011 |
| Faulted | 1,793 |
| Faulty | 1,402 |
| Inoperative | 1,214 |
| Damaged | 737 |
| Contaminated | 589 |
Where in the system the FAA's codes
Air conditioning and pressurisation 7,833Air conditioning and pressurisation 5,995Hydraulic power 2,923Pneumatic 2,589Air conditioning and pressurisation 1,883Ice and rain protection 1,764Air conditioning and pressurisation 1,529Air conditioning and pressurisation 1,460Air conditioning and pressurisation 1,170Hydraulic power 1,038Air conditioning and pressurisation 695Ice and rain protection 684
What the NTSB found accidents and incidents since 2008 in which the NTSB's findings named this system
In 223 cases since 2008 the NTSB named heating, ice protection and utility systems as a cause (111 of them) or a contributing factor; 35 of those were fatal accidents. The part most often named is the ice/rain protection system › intake anti. Among model families, the Piper PA-28 Cherokee, Warrior, Archer and Arrow appears most often. A failure report (above) is a part that failed and was fixed; an NTSB finding is a part that the investigators decided helped cause an accident. The two measure different things, and both are here.
Cases by year
Parts and problems named
Ice/rain protection system › Intake anti108Hydraulic power system › Hydraulic, main system26Hydraulic power system › (general)24Vacuum system › (general)13Hydraulic power system › Pump, main8Air conditioning system › Heating system6Ice/rain protection system › Airfoil anti6Hydraulic power system › Hydraulic, auxiliary system4Ice/rain protection system › Pitot/static anti4Hydraulic power system › Accumulator, main4
Parts the NTSB named, as a table
| cases | |
|---|---|
| Ice/rain protection system › Intake anti | 108 |
| Hydraulic power system › Hydraulic, main system | 26 |
| Hydraulic power system › (general) | 24 |
| Vacuum system › (general) | 13 |
| Hydraulic power system › Pump, main | 8 |
| Air conditioning system › Heating system | 6 |
| Ice/rain protection system › Airfoil anti | 6 |
| Hydraulic power system › Hydraulic, auxiliary system | 4 |
| Ice/rain protection system › Pitot/static anti | 4 |
| Hydraulic power system › Accumulator, main | 4 |
Models most often named
What was wrong last ten years · share of 34,400 reports that say
smoke, fumes, odours or sparks11,763 (34%)a warning light or message10,252 (30%)a false warning3,071 (9%)over temperature593 (2%)other systems affected154 (0.4%)vibration or buffeting112 (0.3%)foreign object damage111 (0.3%)no warning when there should have been102 (0.3%)
As a table
| reports | share | |
|---|---|---|
| smoke, fumes, odours or sparks | 11,763 | 34% |
| a warning light or message | 10,252 | 30% |
| a false warning | 3,071 | 9% |
| over temperature | 593 | 2% |
| other systems affected | 154 | 0.4% |
| vibration or buffeting | 112 | 0.3% |
| foreign object damage | 111 | 0.3% |
| no warning when there should have been | 102 | 0.3% |
When it was found last ten years · share of 34,400 reports that say
cruise6,642 (19%)climb6,135 (18%)descent4,088 (12%)inspection or maintenance3,511 (10%)taxiing or ground handling3,040 (9%)approach1,404 (4%)take-off1,024 (3%)landing723 (2%)
As a table
| reports | share | |
|---|---|---|
| cruise | 6,642 | 19% |
| climb | 6,135 | 18% |
| descent | 4,088 | 12% |
| inspection or maintenance | 3,511 | 10% |
| taxiing or ground handling | 3,040 | 9% |
| approach | 1,404 | 4% |
| take-off | 1,024 | 3% |
| landing | 723 | 2% |
What the crew did last ten years · share of 34,400 reports that say
an unscheduled landing7,298 (21%)an emergency descent1,288 (4%)a return to the gate941 (3%)an aborted take-off516 (2%)oxygen masks deployed159 (0.5%)an engine shut down71 (0.2%)the cabin depressurised42 (0.1%)fuel dumped28 (0.1%)
As a table
| reports | share | |
|---|---|---|
| an unscheduled landing | 7,298 | 21% |
| an emergency descent | 1,288 | 4% |
| a return to the gate | 941 | 3% |
| an aborted take-off | 516 | 2% |
| oxygen masks deployed | 159 | 0.5% |
| an engine shut down | 71 | 0.2% |
| the cabin depressurised | 42 | 0.1% |
| fuel dumped | 28 | 0.1% |
Who filed the report last ten years · share of 34,400 reports that say
an airline (Part 121)30,599 (89%)a charter or commuter operator (Part 135)2,682 (8%)a foreign carrier (Part 129)432 (1%)a repair station (Part 145)327 (1.0%)a non-certificated international operator108 (0.3%)a mechanic64 (0.2%)a private or corporate operator (Part 91)40 (0.1%)the FAA27 (0.1%)
As a table
| reports | share | |
|---|---|---|
| an airline (Part 121) | 30,599 | 89% |
| a charter or commuter operator (Part 135) | 2,682 | 8% |
| a foreign carrier (Part 129) | 432 | 1% |
| a repair station (Part 145) | 327 | 1.0% |
| a non-certificated international operator | 108 | 0.3% |
| a mechanic | 64 | 0.2% |
| a private or corporate operator (Part 91) | 40 | 0.1% |
| the FAA | 27 | 0.1% |
How it was found last ten years · share of 34,400 reports that say
a visual inspection4,880 (14%)a functional check312 (0.9%)a magnified visual inspection10 (0.0%)borescope4 (0.0%)magnetic particle4 (0.0%)thermal imaging4 (0.0%)eddy current2 (0.0%)ultrasound2 (0.0%)
As a table
| reports | share | |
|---|---|---|
| a visual inspection | 4,880 | 14% |
| a functional check | 312 | 0.9% |
| a magnified visual inspection | 10 | 0.0% |
| borescope | 4 | 0.0% |
| magnetic particle | 4 | 0.0% |
| thermal imaging | 4 | 0.0% |
| eddy current | 2 | 0.0% |
| ultrasound | 2 | 0.0% |
FAA orders 305 airworthiness directives · newest first
2026-10-262026-21-02 · Air conditioning system
2026-09-182026-18-01 · Time Limits/Maintenance Checks, Air Conditioning and Pressurization
2026-07-012026-10-10 · Equipment/furnishings
2026-06-262026-10-01 · Pneumatic
2026-02-172025-26-05 · Hydraulic System, Main
2025-09-112025-17-15 · Hydraulic Power
2025-08-292025-16-12 · Pneumatic
2025-04-222025-05-14 · Pneumatic
2025-02-182024-26-04 · Pneumatic
2024-11-122024-18-07 · Equipment/Furnishing
2024-10-292024-16-13 · Ice and Rain Protection
2024-09-252024-14-08 · Pneumatic System
Orders by decade
Who makes and modifies it
Companies the FAA has approved to make equipment for this system (technical standard order authorisations):
Kulite Semiconductor Products INC. 10Arconic Fastening Systems & Rings 5Envirotainer Engineering Ab 3Garmin International INC. 3Honeywell Aerospace US LLC 3Ametek Aerospace 2Diamond J INC 2Sigma Tek, INC. 2Stratoflex, INC. Aerospace & Military Connectors Division 2Aero Systems Mfg. and Overhaul, INC. 1Aeroquip (Canada) LTD 1Aeroquip Aerospace S.A. 1
Approved modifications 736 · the companies holding the most
Air Comm Corporation 26Signature Flight Support Corporation 26Hartzell Engine Technologies, LLC 23Smr Technologies INC 20Jay- Dee Aircraft Supply CO 19Bf Goodrich Aerospace 17Pamco Industries CORP 15Textron Aviation INC 15Brittain Industries, INC 14Smr Technologies 14
Engine series most often named last ten years
Rolls-Royce RB-211 series 84Pratt & Whitney PT6A series 51International Aero Engines PW1133GA-JM 49Pratt & Whitney PW2037 44Allison (Rolls-Royce) 250-C47B 40CFM International CFM56 series 40Turbomeca (Safran) ARRIEL 2B1 40CFM International CFM56-7B27 39Pratt & Whitney Canada PW150A 37CFM International CFM56-5B4/3 35International Aero Engines V2527-A5 32CFM International CFM56-7B27E 25
Safety bulletins 16 · advice, not orders
2026-04-062026-09 · HYDRAULIC POWER, Hydraulic Power Transfer Unit System
2025-01-142025-01 · HYDRAULIC POWER SYSTEM, Fatigue Failure of Hydraulic Flexible Hoses
2021-02-11AIR-21-04 · HYDRAULIC POWER SYSTEM
2013-09-30CE-13-43R1 · Aircraft Fuel Distribution System and Ice/Rain Protection System
2013-08-30CE-13-43 · Aircraft Fuel Distribution System and Ice/Rain Protection System
2013-03-21NM-13-24 · Air Conditioning System: Air Distribution Fan
Sources: FAA service difficulty reports (yearly files since 1995, grouped by the FAA's four-digit system code into this site's fourteen systems), airworthiness directives, supplemental type certificates, technical standard order authorisations and special conditions from the FAA's Dynamic Regulatory System. Rates per 100 aircraft use today's register as the fleet; they show reporting as much as reliability, and commercial fleets report more. Connections as data: /graph/system/utility.json.