What Were Jabiru’s Engine Problems in The Past?

Jabiru Aircraft Engine Problems (ATSB & CASA’s Report)

Jabiru Aircraft is the leading manufacturer and exporter of light aircraft engines in Australia. While it has been operational since 1988, the family-owned business has seen a significant number of engine failures between 2009 and 2014. During the six years, 130 cases of Jabiru aircraft engine problems occurred, representing 40% of the total aircraft engine problems reported to the Australian Transport Safety Bureau (ATSB).

However, a critical look at the ATSB report indicates the potent possibilities of a biased piece to the disadvantage of Jabiru Aircraft. The report’s flaws could be why the transport safety regulatory body rescued the aircraft engine manufacturer. 

The ATSB study involved a 6-year analysis of aircraft engine-related problems in the region. Below are some of the report’s details related to Jabiru.

  • There was no fair balance of the engines analyzed by the transport safety regulator. Jabiru aircraft engine problems, together with three other competitors’ engines, amounted to 94% of the total machines included in the report.   
  • The engines used by Jabiru were a famous brand in Australia and used by most airline companies. Most experimental and home-made aircraft use the same type of machine.

Safety Measures to Minimize Jabiru Aircraft Engine Problems

It’s worth noting that most of the incidents (almost 50% of the 130 Jabiru aircraft engine problems) were due to fractured components in the planes’ engines. A significant part that had a frequent tendency to malfunction is the through-bolt, which saw 1 in every 10 aircraft engine problems involving Jabiru Aircraft.

The above facts, notwithstanding, fatal cases from the aircraft incidents indicated that Jabiru Aircraft had the best safety precautions throughout the region. For every 100 aircraft registered in Australia, only 0.3 involved Jabiru Aircraft. Jabiru’s fatality rate isn’t comparable to the 1.8 fatalities for 100 reported Cessna 172s aircraft in the 12 years before the study. Similarly, Vans RV aircrafts recorded 2.2 deaths for every 100 registered planes during the same period. 

The following are some of the safety measures that helped to minimize Jaribu aircraft engine problems;

Most of the Jabiru-owned aircraft were lightweight. The low weight allows pilots to maneuver quickly, even in the absence of power.

  • The company complied with a regular aircraft maintenance exercise. The repair of through-bolt engine problems followed the safety regulator’s requirements. 
  • The planes were flown by experienced pilots to leverage on the low-power engines.

Additionally, the Australian aircraft engine manufacturer met all ATSB safety requirements. These include flying low when passing over populated areas, with daytime flying restriction. Passengers and pilots were also required to accept the possible Jaribu aircraft engine problems through a signed statement.

Jabiru Aircraft Through Bolt Problems

Through-bolt refers to an aircraft’s accessory, a bolt responsible for keeping the engine crankcase in place. It plays a vital role as the plane engine’s piston is located in the crankcase. When pistons are tampered with or malfunctions, the aircraft’s mobility will be compromised, leading to possible accidents. The damaged bolt was the primary cause of most Jabiru aircraft engine problems in the past.

There are two types of through-bolt in aircraft engines exits. One has a diameter of 3/ 8 inches and was popularly used in Jabiru engines during the six years to 2012. The other one has a diameter of 7/ 16 inches, which is larger and has less failure reported than the 3/ 8 one, according to the ATSB report. 

Several incidents of Jabiru aircraft engine problems were caused by the old version of 3/ 8 inches through bolts. During the six years of ATSB’s study on Australian aircraft safety, these bolts caused 21 of the Jabiru engine’s failures. For Jabiru Aircraft, 1 in every 55 (1.8%) engine failures resulted from the 3/ 8 inches through-bolt. 

Upgraded versions of the 3/ 8 inches through bolts are safer to use in aircraft engines. There were only four incidents of engine failures for planes using this upgraded bolt. About 20% of Jabiru aircraft have the 7/16-inch through-bolt. While there are no reported engine failure incidents for planes using this through-bolt, there is no sufficient information to tell if it’s safer than the 3/ 8 one. According to ATSB’s report, the lack of engine failure for aircraft using the thicker through-bolt may be due to their use on a few aircraft and the aircraft’s relatively low time-in-service.

How Through-Bolt’s Failure Causes Engine Problems

An aircraft doesn’t lose its power instantly when the through bolts fail. Instead, the reduced force that holds the engine’s case to the cylinder will be compromised, making the extra load redistributed to three other through bolts. Please note that the four through bolts’ location is on the adjacent sides of the engine’s two cylinders.

The weight added to the other three cylinders will serve to reduce the engine’s combustion pressure gradually. Eventually, the bore clearances will tighten and make the engine’s piston to bind. The plane will start progressively to run roughly after some time. Failure to resolve this situation in time may lead to fatal results.

For safety reasons, it’s best to take appropriate precautions to prevent possible engine problems. The following could help;

  • Pilots should check for possible indicators of Jabiru aircraft engine problems. Oil leaks around the engine’s cylinders are a significant indicator of a tightened engine. The checks are necessary before commencing any flight. 
  • Pilots should conduct a pull test on the aircraft’s propellers before commencing the first flight of the day. Reduced propeller action could indicate a problematic engine. However, this test will be difficult for inexperienced pilots.
  • Conducting physical checks to ensure through bolts are functioning correctly. This check should be done at regular intervals or when pilots report a rough running.

Jabiru Aircraft Safety Measures to Mitigate Through Bolt Failure

An upgraded 3/8-inch diameter through-bolt has been designed and tested by Jabiru Aircraft. This modified through-bolt design serves to prevent engine failures by addressing its thermal expansion and rough running. For the period these bolts have been tested, only four through bolt-related engine failures have been reported. 

The aircraft engine manufacturer has also made use of the advanced 7/16-inch diameter through bolt. Their large size makes it hard for the plane’s engine to tighten, leading to reduced engine failures. To date, 20% of Jabiru engines are fitted with these through bolts. Similarly, planes that use a 7/16-inch diameter through bolts have not reported any engine failures.   

Jabiru Aircraft Valve Problems

engine valves play a vital role in aiding the proper functioning of an aircraft. The gases produced by the engine’s combustion are balanced and controlled with valves. When they are broken or in poor working condition, the inability to regulate gas from the plane’s cylinder will result in engine failure and a potential accident.

ATSB’s investigation concerning Jabiru aircraft engine problems highlighted several factors that caused the engine failure incidents. The studies followed a series of engine failures (mostly focused on planes powered with Jabiru engines) for the six years to 2014. However, fractures in engine components contributed to the incidents. Besides through-bolt and freewheel bolt problems, the engine’s valves were also part of the causes.   

What has remained unclear, however, is the number of Jabiru aircraft engine problems that were a direct consequence of failed valves. The report provided by Australia’s transport safety regulator, ATSB, did not give any details to this effect. Despite the lack of clarity, you should note that 21 of the 130 reported incidents involving Jabiru engines were caused by failed through bolts. The role played by through-bolt in plane engines is closely related to -valve’s function. As such, high chances are that valve problems contributed to an almost similar number of engine failures. 

What Was the Impact on Jabiru Planes Due To Valve Problems?  

Many factors can make valve engines to fail. However, an aircraft can only lose absolute power when the valves’ damage reaches the extent of making them open. The supply of gas from the cylinders is compromised when the pistons are damaged, resulting in the gradual loss of power. Severe damage to the aircraft engine valves (mostly involving stem bending) will cause more damage to subsequent engine pistons. The result will be rough running caused by constant vibrations and a complete loss of power.

Besides the causes mentioned above, valves can malfunction when overheated. The excessive heat may make the valves fall into the engine’s cylinders resulting in power loss. Valves may find themselves inside the cylinder when the retaining system fails. In such a case, the result may be catastrophic.

There will be no impact on the plane’s pistons if the valves are not fully stuck. Instead of experiencing power loss, the aircraft will go through rough running. A similar situation will be shared when springs fail in a plane configured with double springs. The pistons used in new Jabiru engines feature an additional space in its head, referred to as the crown. If the aircraft valve engines open up, the added feature will provide relief to the engine. While there will still be rough running, clearance will reduce the impact and prevent power loss. 

Please note that the engine head’s additional feature will not help if valves drop into the cylinder.

Actions Taken By Jabiru Aircraft to Solve Valve Problems

Jaribu aircraft engine problems have benefited from the lightweight associated with their planes. The small weight allows for pilots to maneuver the aircraft easily, even with reduced power. However, CASA’s report highlighted that the Jabiru engine’s reliability required an advanced approach to its maintenance. The report highlighted the fact that the manufacturer’s engine variation recommendations were not practical. Before that, Jabiru Aircraft was not aware of this. 

Following the report’s release, the Australian aircraft engines manufacturer and seller rolled in new measures to curb valve issues. The company acknowledged not knowing the advanced maintenance needs of its engine cylinder head and valves. The acknowledgment was through a comprehensive Service Letter, referenced JSL014-2, which was issued in December 2014.

According to the Service Letter, Jabiru had implemented a rigorous maintenance course and adopted the best practices. An additional feature to its engine’s head was one of the implemented measures. The added feature served to prevent valve problems or reduce the plane’s impact when it happens.  

CASA Operational Limitation

A few years preceding 2014 saw a series of Jabiru aircraft engine problems. While several factors played a role in the engine failure incidences, the aircraft’s loss of power due to unreliable engines was the primary cause. The Civil Aviation Safety Authority (CASA) had no choice but to step in and try to reduce such events from happening.

The transport safety regulator had the idea to revoke the Jabiru engine’s licenses in totality from the onset. However, subsequent consultation with the industry’s stakeholders (including Recreational facilities, Jabiru Aircraft, and Sports Aviation Association) led to the opposite. Instead, the regulatory body introduced a set of measures for the aviation industry to reduce engine failures. These limitations touched on experienced and trainee pilots and their flight passengers. 

Operational Limitations as Detailed in CASA’s Legislative Instrument

The primary concern of the proposed legislation limiting aviation operations, termed as CASA292/14, was to address Jabiru aircraft engine problems. While increased combustion pressure and reduced power were the leading causes, the possible failures posed a significant risk to other people. The piece of legislation intended to strike a perfect balance that catered to the needs of both parties. These included aviation industry businesses and the persons facing the risk of possible engine problems. 

In a statement released by CASA to the media on 20 December 2014, the following were noted;

  • Jabiru aircraft engine problems were majorly caused by through bolts and flywheel bolts. The aircraft’s valve train was also found to contribute to the problem. These caused engine cylinders to crack, resulting in reduced power and rough running. 
  • The problem was found to affect different plane models fitted with Jabiru engines. While the planes were used for various activities, most of them were used to train pilots. 
  • The transport regulator worked closely with the affected firm, Jabiru Aircraft, and other aviation industry stakeholders. The statement asserted their commitment to addressing the problems and coming up with appropriate solutions. 
  • Other investigations were ongoing to verify and obtain more facts. The subject of the inquiry touched on the engine’s design and mechanical component. It also focused on how the planes were flown and maintained.

Another statement was issued on 23 December 2014. This second media release served to impose operational limitations on specific companies. Those affected were aviation companies that were licensed or under one contract with Jabiru Aircraft. Aviation companies using Jabiru engines were included, too. The limitations were to the effect that these companies would manage the risks associated with engine-related failures. 

On 1 July 2015, CASA re-issued the directive allowing Jabiru aircraft to resume its passenger operations. However, the new direction was applied with the condition that Jabiru complies with ATSB’s recommended aircraft maintenance.

Impact of the Limitations and Way Forward

The purpose of CASA’s legislative instrument was made clear by an Explanatory Statement that came with it. The need to mitigate the possible risks caused by planes powered with Jabiru engines was a top priority for affected users. At the same time, the industry regulator emphasized its role in finding appropriate solutions together with Jabiru.

Similarly, the Explanatory Statement acknowledged that several Jabiru models were affected by engine failures. It identified through-bolt problems, valve and cylinder issues as the possible cause of the problem. It continued to add that the affected planes were used for many activities. 

Consequently, limitations were imposed on aviation operators with engines from Jabiru. Pilot training institutions were not left out either. These limitations required that;

  • Night flights were to be canceled. Aviation operators needed to fly during the day due to visual flight rules.
  • Aircraft should only be flown in such a manner that they can glide from a populated area. Pilots were required to pass low in such sites.
  • If passengers or pilots were to fly solo, they would be required to acknowledge and accept the potential risks. Flying solo required them to sign a consent form before flying.
  • If trainee pilots were to fly alone, they would have to complete exercises on engine failure.

Were the Proposed Operational Limitations Feasible?

When the new limitations came into force, a wave of debate arose about whether the terms of the legislation made sense. However, one thing was exact; most aviation companies were not satisfied with the new rules. Despite the widespread talk, many knew that the limitations would bring changes (minor changes) to help prevent aircraft engine failures.

An important thing to note is that the proposed legislation was to last for six months from the implementation date. The six months was meant to give time for the investigations on engine failure causes to be completed. The same period also involved coming up with practical solutions to curb the incident.

The question on many people’s minds was; is six months enough to make this possible? While there was no clear answer to this question, one thing was evident: a potential extension to this date. Failure to address the issues within the six months would call for an extension. Besides, the ongoing investigations may have required historical data or specific details from the manufacturer. More time would have been required to do this.

Besides, other crucial factors had to be considered concerning;

  • How will the six-month period affect companies in the aviation industry?
  • Why didn’t the transport regulatory body address the safety concerns before Jabiru aircraft engine problem?

What Role Did OBPR (Office of Best Practice Regulation) Play in Impact Evaluation?

There’s no doubt that flying schools were the biggest losers of the proposed legation. Having said this, it beats every logic to understand why CASA did not evaluate how the limitation of aviation activities will impact flying schools. It should be noted that the legislation came into force during a period associated with high flying activities; December. The situation was made worse by asserting that the new aviation rules would have minimal effect on flying schools. This claim was included in the Explanatory Statement issued by the Office of Best Practice Regulation OBPR.

The OBPR is forms part of the Prime Minister’s Department and the Cabinet. The Australian Government has tasked this office to evaluate the impacts of proposed regulations. Before any new legislation is passed (or an amendment to existing legislation), OBPR must be consulted to determine if an evaluation is required. If a bill would interfere with businesses’ daily running when introduced, OBPR should advise against it.

CASA’s proposed restrictions were going to affect flying schools and their students. In line with best practice principles, the relevant regulatory body ought to have demanded prior evaluation. The Australian body tasked with transport safety should have issued a detailed evaluation analysis, referred to as Regulatory Impact Statement (RIS). The statement would clearly show the costs and benefits of the proposed limitations.

Jabiru’s Response to ATSB & CASA

2014 was not the best year for Jabiru Aircraft. The high number of Jabiru aircraft engine problems at the time led to widespread concern over the engine’s safety. What followed was an investigation that culminated in the release of a detailed report by ATSB. Additionally, the country’s civil aviation body imposed limitations on planes powered by Jabiru engines. How did the aircraft engine manufacturer respond to these two organizations?

How Jabiru Responded to the Report’s Findings

Through its Managing Director, Ms. Woods, the findings made by ATSB’s report were biased, flawed, and not in line with the aviation industry’s best practices. Jabiru claimed that the information had unfairly focused the investigations on specific aircraft engine models. Out of the 322 engine failures investigated, 130 involved Jabiru engine-powered planes. The response argued that the conclusions made could not be applied as it had many loopholes.

According to Jabiru’s manager, the fatalities recorded by Jabiru engines were way below the industry safety standards. Several aviation companies in Australia had higher fatality rates compared to Jabiru. Earlier reports were in line with this claim. Indeed, most of Jabiru aircraft engine problems involved minor incidences and low fatalities. The Queensland-based company eliminated any doubts concerning the safety of its engines.  

The company continued to argue about the causes of engine failures investigated. While ATSB and CASA focused on mechanical faults, other factors were not considered. The report didn’t consider factors in pilot error, issues with fuel (running out or contaminated fuel), and the prevailing weather conditions. The elements not considered could affect any aviation operator other than Jabiru.

Jabiru engines were a famous brand in Australia at the time and used by several individuals and organizations. The engines were a cheap brand that made them suitable for experimental, home-made aircraft. They also involved less maintenance than other versions of aircraft engines. Jabiru’s response highlighted the report’s failure to factor in this issue. Additionally, Jabiru engines were ideal for light aircraft. It served to make it easier to control the plane when its engine has failed and power lost. In the report, ATSB defined light aircraft as those not weighing more than 600kg. Jabiru claimed 800kg as the industry’s standard rate, and ATSB’s figure was biased to their disadvantage.   

How Jabiru Responded to the Imposed Limitations

Jabiru Aircraft had issues with CASA’s proposed legislation to limit aviation operations by Jabiru-powered planes. A statement released to the media in December 2014 called for the immediate assessment of the imposed limitations.

According to the issued statement, Jaribu was having talks with relevant bodies, including CASA. These talks were aimed at improved communication to build a harmonious relationship with regulators, manufacturers, and administrators in the aviation industry. Jabiru went ahead to commit to creating an active, functional, and safe environment for the industry. 

Jabiru’s statement made it clear that its staff and engineers worked with CASA engineers to address technical concerns. The talks resulted in Jabiru sharing its engineering reports, a thing they never did in the past.

Following talks between Jabiru and CASA engineers, the company later came up with a comprehensive Service Letter. The letter’s purpose was to aim at minimizing potential Jabiru aircraft engine problems in the future. The renowned manufacturer continued to claim their intentions of rolling out complete maintenance training to address engine faults.

Final Thoughts

Like any other industry, aviation operators have their own set of challenges, similar to Jabiru aircraft engine problems. What matters most is the actions taken to resolve these issues. The information shared in this post has highlighted the challenges faced by Jabiru Aircraft back in 2014. A detailed analysis of its engine failures, covering the six years from 2009 to 2014, has been provided. The post includes limitations imposed and how the Australian-based aircraft engine manufacturer and seller worked around them.

It is important to note that you should not consider the information shared here as blame or liability to any specific individual or organization. This post aims to share valuable and practical knowledge with aircraft students, operators, and enthusiasts.


Question: How safe is Jabiru engines?

Answer: To appropriately answer this question, it would be better to understand your need for the engine. The safety of the Jabiru engine is guaranteed if used according to the manufacturer’s specific recommendations. These recommendations include;

  • The engine is ideal for use in powering light aircraft with a maximum weight of 800kg.
  • The engine should undergo regular maintenance and improvements in line with the best industry practices.
  • Inspection of the engine is necessary every time before takeoff.

Following the above plus other recommendations from the manufacturer will keep you safe with the Jabiru engine.

Question: How often should a pull test be conducted on Jabiru engines?

Answer: Conducting a pull test every time before takeoff is unnecessary. For the best results, you should try to do this as regularly as possible. A better thing to do is to check the aircraft before the first flight of the day. However, a test is necessary any time the plane depicts signs of engine problems.

Question: What options does an aircraft operator have against the imposition of limitations from bodies like CASA?

Answer: In most cases, the imposition of limitations is vital to protect all aviation stakeholders. It has a positive purpose, and the affected operators have no option but to comply with them. However, certain impositions tend to impact individual operators negatively.

If you think that imposed limitations hurt your aviation business, you have the right to seek their reconsideration. Lifting imposed limitations will require you to follow the right legal channels to avoid breaking the law. The revocation of these restrictions is possible (in totality or for your specific case) if your case is proved valid. Similarly, your business’s lost revenue due to the limitations will call for immediate compensation.

Question: What is the best way to address a negative impact on a business due to aviation restrictions?

Answer: To start with, have you evaluated if your business is directly affected by the limitations? You have to conduct a cost-benefit evaluation to establish your case. In Australia, regulatory bodies have the responsibility to ensure the rules are ideal for all stakeholders. Such companies are supposed to file a Regulation Impact Statement (RIS) with the Office of Best Practice Regulation (OBPR). If the proposed limitations disadvantage your company, the RIS will reflect this, and the OBPR will have no option but to resolve the issue. However, some bodies may avoid this process, so you have to take your case forward. 

Question: How long do limitations placed on the aviation industry last?

Answer: Well, the length of the limitations will depend on the issue at hand. The purpose of any restriction is the protection of stakeholders. For Jabiru’s case, the regulations aimed at protecting people from the potential risks of engine failure. For this reason, the limitations will remain in place until the matter has been resolved, and the risks are prevented or reduced. 


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