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B737 MAX back in the air? Not so fast... (amended 11-Aug-2021)

Updated: Aug 11, 2021

On the 18th November, FAA administrator, Steve Dickson, signed Rescission of Grounding in order to rescind the Order of Prohibition that was standing and as a result of which the US registered aircraft were grounded, following the grounding of the type elsewhere in the world almost two years ago.

In this post I would like to show that this is only the start of events to meet the conditions to get the 737 MAX back in the air and hopefully be as safe and successful as its predecessors; the 737 classic and NG versions.

Below the Signed Order Of Rescission, also available on the FAA website.

Download PD • 3.92MB

Please note that FAA was the last of the Civil Aviation Authorities to ground the type after the two fatal accidents in Indonesia and Ethiopia respectively.

The first to ground the type were the Chinese CAAC, followed by the UK CAA and EASA subsequently.

The substantiation for the rescission of the grounding is below summary of certification amendments and other considerations for measures to enable the return to service of the type. Document titled 737_RTS_Summary.

FAA compiled this document in which is documented what considerations were made and exactly were the grounds for these measures.

The document is downloadable for interested readers and also available on the FAA website.

It contains Airworthiness and operational measures that were taken and ultimately resulted in the issue of the NPRM (Notice of Proposed Rulemaking), meant to gather public comments, preceding issue of the final rule which has also been issued with effective date November 20, 2020 .

Unfortunately this post is too short to, even briefly, summarise the various airworthiness aspects of the grounding and subsequent re-certification of the type. There are a few posts containing more technical data on this website in which the NPRM is reviewed and an other one reviewing the Airworthiness elements which also contains the official accident investigation report for Ethiopian Flight 302 and Lionair flight 610.

Download PDF • 3.22MB

Below is the AD for download for interested readers.

FAA went to great length to show the number of comments and replies from FAA. This alone reflects the critical attitude from the Aviation community towards the return to service for the type.

Some commenters even requested the FMEA (failure Mode and Effect Analysis) for review. This is a highly uncommon move and requires in-depth aeronautical knowledge and familiarity with the particular aeroplane design to interpret. This is indicative of the general mistrust of the commercial aeroplane certification process.

An abbreviated list of some commenters;

  • Families of Ethiopian Flight 302

  • Ethiopian Airlines Group

  • BALPA (Britisch Airline Pilots Association)

  • Turkish DGAC

  • UAE GCAA (Arab Emirates CAA)

  • ALPA (Allied Pilots Association)

  • NATCA (National Air Traffic Controllers Association

  • A4A (Airlines for America)

  • Boeing

  • SWAPA (Southwest Airlines Pilots Association)

  • Air China

  • Ameco (Chinese MRO)

  • Flyers Rights

  • Aerospace Safety and Security Inc.

Download PDF • 1.90MB
2020-24-02 EASA decision
Download PDF • 514KB

With Regards to the FAA conditionally (compliance with the actions stipulated in AD 2020-24-02) releasing the type for service, other Aviation authorities have not yet released the type of aircraft on their registry. Among them the Chinese CAAC and also EASA.

In fact, EASA went as far to explicitly not adopt AD 2020-24-02. Below is a explanatory note published by EASA.

Under FAA / EASA bilateral agreement (spelled out in the TIP), both regulatory agencies accept each others substantiation and validation data. This previously agreed practice seems not to be as rock solid as it has always been. Increasingly, foreign regulators being more critical and hands-on in certification and safety issues. This potentially complicates international Continuing Airworthiness Management.

Please also note that among other regulators, both ESA and CAAC have been involved in the Return to Service of the type.

These two fatal accidents took the lives of nearly 350 unsuspecting people, consequently permanently affecting the lives of thousands left behind.

The commercial Aviation community must take a good hard look as to what went wrong and this is a good beginning, not only to get an aircraft back to the skies but to commercial air transport safety in a broader sense, which includes public trust in the industry

Amendment 24-Nov-2020

EASA published today a "PAD" (Proposed Airworthiness Directive) for public consultation addressing additional actions before releasing the type for service.

This PAD (downloadable below); once in force, would be the gateway to service instead of AD 2020-24-02 which was not adopted by EASA. Only for EASA countries registered aircraft though!!

The PAD summarises the actions; both Operational as well as Airworthiness wise, conditions to release of the type. It also identifies where the EASA (Proposed) AD differs from, or is an addition to the FAA AD and where it conforms the FAA AD. This begs the question, that, in case of an export from FAA to EASA or vice versa, how these actions would be validated in both jurisdictions. To be continued....

Download PDF • 866KB

Amendment 2-Dec-2020

While in the US, the first certificates of Airworthiness have been issued for the 737-8/-9 (MAX in more popular terminology), EASA still has the PAD (Proposed Airworthiness Directive) in consultation phase prior to issuing the final rule.

Once consultation has been obtained and answered, EASA will issue the final rule after compliance of which, operators can start using aircraft of the type again.

Meanwhile, EASA has issued a PSD (Preliminary Safety Directive attached below). The PSD is, like the PAD, a preliminary document that, when finalised and activated, directs operators located outside EASA to comply with it, when flying into EASA airspace. Operators located outside EASA territory flying into EASA airspace normally operate under Part TCO (third country operations) regulations and need to demonstrate compliance with it.This is similar to the FAA Part 129 regulations which foreign operators need to show compliance with before operating into the USA.

The PSD specifies compliance with FAA AD 2020-24-02 (remember contains overlapping, but not the exact same requirements as EASA PAD 20-184) and in addition:

Requires pilots to undergo RTS (Return To Service) training contained in FAA FSB (Flight Standardisation Report Rev. 17 Appendix 7). These requirements are also stipulated in EASA PAD 20-184 but not in FAA AD 2020-24-04. The training must be conducted in a Full Flight Simulator as specified in the FSB

  • FSB document attached below (Appendix 7 is on page 65 of the document)

  • EASA PSD 20-185 attached below.

Download PDF • 417KB

Download PDF • 729KB

Amendment 25-Jan-2021

In Dec 2019 Edward Pierson testified in US congress in relation to the Committee's investigation into the 737 MAX accidents. (Congressional report downloadable from my blog "Safety Culture and Regulators"). He had retired from Boeing as a senior manager at Renton production facilities in August 2018 and had expressed his concerns over the production challenges and safety implications at Boeing Renton to 737 General Manager.

Recently he produced a report that reflects the production challenges and quality issues at time of production of both the accident aircraft of Lion Air and Ethiopian Airlines.

His report is downloadable from his own website

It is a 14 page account of:

  • A multitude and excessively high rate of electrical- and flight control defects of the accident aircraft prior to their accident flights that have not been brought into the assessment of the probable contributing factors of the accidents.

  • discrepancies found in numerous Angle of Attack (AOA) sensors that were related to design and production of these units.

  • A production line that was under high duress with excessive amounts of traveled work and repairs as a result of an overstressed supply chain and workmanship issues with wiring, that caused a high rate of test failures and repairs during production.

  • At least 13 additional safety events on 737MAX airplanes built in the same time period of the Lion Air and Ethiopian aircraft.

  • AOA sensor heating affecting sensor output as a common factor in both accidents.

His report queries why no emergency AD was issued for the consistent failures of the AOA sensors. He also indicates that there may be other Electrical Wiring Interconnect Systems (EWIS) problems about to emerge. Quoted below:

"The failure of an originally installed Boeing part involving an open circuit, wire fatigue and evidence of multiple arcing events, and a factory environment under duress with a shortage of electricians, a high number of quality reports involving EWIS defects and chronic functional test failures is cause for serious concern. The 737 MAX’s electrical system is also significantly different than the 737 NG requiring a more complicated build plan—given the new engines, new APU and many miles of wiring infrastructure.

“It may be easier to find a needle in a haystack than to navigate an aircraft’s electrical system, which can include miles of wiring and thousands of connectors and plugs.”51 "

One of his closing statements:

"The design of the 737 MAX, MCAS software and the failure to provide vital information and training to pilots did not trigger these accidents. Neither did corporate decision making made years ago, unethical behavior, deceptive marketing, or a misguided leadership culture that prioritized profits over safety. Nor did deregulation, regulatory capture, or a completely broken aircraft certification process. In fact, all of these things contributed mightily to these tragedies. Unfortunately, every MAX airplane ever manufactured shares this same wretched history. The pilots are certainly not to blame. They did everything they could to save the lives of the people who trusted them. The triggering event for these crashes was a defective AOA Sensor part, and quite possibly, a malfunctioning electrical system stemming from a dangerously unstable production environment."

Ed Pierson's full report downloadable below (posted with his permission):

737 MAX - Still Not Fixed
Download PDF • 388KB

Amendment 27-Jan-2021

Today EASA issued the final rule to PAD (Proposed Airworthiness Directive) 20-184. Because new year was between the issue of the PAD and the final rule, the number has changed.

Final AD is numbered 2021-0039.

Downloadable below:

Download PDF • 385KB

Revision 1 of the EASA AD below

Download PDF • 389KB

Revision 2 of the EASA AD below

Download PDF • 389KB

The content of the EASA AD differs considerable from the FAA AD 2020-24-02 issued last year.

During the consultation phase of the EASA PAD, 38 commenters submitted their comments to EASA pertaining the the content. All comments have been documented in below document.

This Comment Response Document (CRD) is a 78 page monster and contains all submitted comments and responses. Some have been rewarded but most have been rejected.

There are some very detailed comments from very knowledgeable parties like Airline Pilot Associations, Boeing as wel as several Aviation Safety Agencies.

Download PDF • 1.09MB

Generally AD's are issued supplemental to Type Certificates and contain conditions, every applicable aircraft has to comply with, in order to mitigate potentially unsafe conditions. In the event of an annual Airworthiness Review, compliance to the letter of each paragraph has to be demonstrated.

In the EASA AD, generic conditions are published such as pilot training and training methods. This is difficult to demonstrate legally when an aircraft changes operator or is imported or exported because it does not pertain to the aircraft itself but to the operator; if the aircraft is in operation. It will require flexibility from Airworthiness Authorities to accept and certify individual aircraft.

Every EU registered aircraft now needs to be shown to comply before being certified to operate:

Summarised below (refer to AD for certified content!!) using the compliance paragraph numbers in the EASA AD:

  1. Installation/test of te revised Flight Control software.

  2. Installation of Stick shaker cutout button (not part of the FAA AD 2020-24-02)

  3. Aircraft Flight Manual (AFM) amendments (different from FAA AD2020-24-02)

  4. Master Minimum Equipment List (MMEL) amedment (different from FAA AD2020-24-02)

  5. Installation/verification MDS (MAX Display System) software

  6. Horizontal Stabilizer Trim wiring loom routing modification

  7. AOA (Angle of Attack) sensor system test

  8. Operational Readiness Flight (content differs from FAA AD2020-24-02)

  9. Credit for previous modifications and FAA AMOC's ( Alternate Means of Compliance)

  10. Return to flight Operations requirements stating that compliance with all of the above cancels the grounding of the type in EU jurisdiction. (not part of the FAA AD2020-24-02)

  11. Training Requirements (limited to pilots, interestingly not to technicians) Not part of the FAA AD2020-24-02

  12. Full Flight Simulators used for pilot training. (Not Part of the FAA AD2020-24-02)

  13. Pertains to Full Flight Simulator requirements.(Not Part of the FAA AD2020-24-02)

  14. Pertains to 737 NG Flight Simulator control forces. (Not Part of the FAA AD2020-24-02)

Below downloadable, the EASA certification report. This is a high level overview of the Investigation activities related to the 737 MAX Return To Service.

Download PDF • 1.13MB

For foreign (non EU) 737 MAX operators that are not bound to comply with the EASA AD 2021-0039 (because their aircraft are not subject to EU jurisdiction) the below SD (Safety Directive) applies as part of Part TCO (Third Country Operations) requirements for operating into EU.

Download PDF • 207KB

AMENDMENT 11-Aug-2021

Early August 2021 the Boeing 737 MAX test aircraft flew to China.

Chinese Aviation Authorities (CAAC) are the last of the major Aviation Authorities to re-certify the type and subsequently allow it to resume service after global grounding of the type, following the two well published fatal accidents in Indonesia and Ethiopia in 2019.

Accident reports in another post on this website.

Like EASA,CAAC broke with the ICAO Annex 8 agreement, that Airworthiness regulations issued by the State of Design of the Type Certificate Holder are followed.

EASA did their own safety review on the after the issue of the Return To Service study was published and had designee's travel over to Seattle to conduct their own test flight before issuing their own AD (see above) which differ considerably from the FAA AD.

Now it seems that the Chinese Authorities are following the same path and will test fly the aircraft from Shanghai. See report from Flight Magazine below.

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