SUBJECT: Operation of Wide-Body Jets with Door/Slide Inoperative

-------------------------- MMEL GLOBAL CHANGE ----------------------

PL-1 is designated as GC-149

This GC is an approved addendum to all existing MMEL documents.  The operator may seek use of the specific relief contained in the policy letter by revising the Minimum Equipment List (MEL).  In doing so, the sample proviso stating the relief in the policy letter must be copied verbatim in the operator's MEL.  Approval of the revised MEL is gained utilizing established procedure, through the assigned Principal Operations Inspector (POI).

=========================================================================

PL-1, Revision 3                                      Jan-04-2008

 

SUBJECT:    Operation of Wide-Body Jets with Door/Slide Inoperative

 

MMEL CODE:  25 and 52 (EQUIPMENT/FURNISHINGS and DOORS)

 

REFERENCE:  PL 1, R1, dated August 8, 1995

            PL 1, R2, dated August 15, 1997

 

FROM:       Manager, Air Transportation Division, AFS-200

 

TO:         All Regional Flight Standards Division Managers

            All Aircraft Evaluation Group Managers

 

REPLY TO

ATTN OF:    Manager, Program Management Branch, AFS-260

 

PURPOSE:

To allow relief for Operation of Wide-Body Jets with Door/Slide

Inoperative.

 

DISCUSSION:

Policy Letter No.1, Revision 1, provided information on changes to the original Policy Letter No.1, dated August 14,1974. The original policy allowed Master Minimum Equipment List (MMEL) dispatch relief on the L-1011, DC-10, and B-747 airplanes with one door/slide inoperative in accordance with specified conditions. Later, this authorization was extended to the A-300-B3/B4 and the MD-11.

 

MMEL PL-1, Operation of Wide Body Jets with Door/Slide Inoperative, was amended by Revision 1 to the extent to provide for the new policy and provisions set forth herein to allow dispatch with one door/slide inoperative on certain air carrier aircraft.

 

Revision 2 standardizes the format with other Policy Letters,

with no change to policy.

 

Revision 3 added “or slide missing” to the All Freighter Configuration and All-cargo and Combination Passenger/Cargo Operation relief.

 

PL-1 provided for minimum equipment list (MEL) relief by allowing exit door/slide to be inoperative on the B-747, DC-10, and L-1011 airplanes according to the parameters set forth in a Federal Aviation Administration (FAA) staff study dated February 26, 1974.In 1978, similar relief was extended to the Airbus A300-B2/B4 aircraft and the MD-11 was granted relief when it was introduced into service.

 

The introduction of the wide-body aircraft technology resulted in new requirements for aircraft evacuation, notably higher floor sill heights, and greater passenger capacity.  The FAA also introduced regulations requiring that emergency exits be equipped with inflatable escape slides which deployed automatically upon exit door opening. Regulations further required that these exits be armed for auto deployment during all ground operations.

 

Technological problems arose with the automatic inflation features of the escape slides.  A larger problem that resulted was the frequency of inadvertent slide deployments caused by airline employees and ground service personnel opening the doors before the slides were deactivated.  With each of these occurrences, the aircraft was "grounded" until replacement slides were installed.  Despite measures taken by the aircraft manufacturers and operators to reduce the number of inadvertent door/slide deployments, the need to continue relief for the subject airplanes is clearly evident.

 

During a joint FAA/industry meeting on December 1, 1994, the FAA PL-1 regarding an inoperative door/slide was reviewed to determine if dispatch relief currently granted could include other wide-body, twin-aisle airplanes such as the B-777, A300-600, and B-767. In attendance at this meeting were representatives from FAA (AFS-200 and AFS-300), Air Transportation Association of America, Airline Pilots Association, Allied Pilots Association, Association of Flight Attendants (AFA), Boeing, Airbus, as well as American, Delta, Northwest, Trans World, and United Airlines. All representatives solidly supported a MMEL proposal for door/slide relief on all wide-body, twin-aisle airplanes except the AFA representative who indicated opposition to the plan.

 

Subsequently, other organizations such as International Association of Machinist indicated support to the proposed door/slide MMEL relief while the Association of Professional Flight Attendants opposed the proposal.

 

POLICY:

The FOPB, in review of the industry data and service experience, has determined that there is sufficient technological justification for permitting MEL relief for the door/slide to the A300-600, B-767, and B-777 airplanes.

 

Appendix A, attached, provides guidelines for chairman of the appropriate Flight Operations Evaluation Boards in preparing the MMEL relief for a door/slide to be inoperative for wide- body, twin-aisle airplanes.  MMEL revisions are to be completed for the A300-600, B-767 and the B-777 as soon as practical. These new guidelines are essentially the same as those now in effect and current MMEL approvals for door/slides need not be amended.

 

Appendix B, attached, contains pertinent data in support of MEL relief for wide-body, twin-aisle airplanes.

 

Appendix C, attached, contains discussion on safety issues.

 


Attachments

 

APPENDIX A

 

52

DOORS

 

 

 

 

 

 

 

 

 

 

XX

Main Entry Door/Slides

 

 

 

 

 

 

 

 

 

 

 

1) Passenger Configuration

A

-

-

(M)(O) One door may be inoperative or one slide missing provided:

a)      All other main entry doors are fully operational,

b)      Affected door is not used for passenger loading,

c)      A conspicuous barrier strap or rope and a placard stating that the door is inoperative shall be placed across the inoperative door,

d)      Emergency exit sign and floor proximity lights associated with the inoperative exit must be covered to obscure the signs and lights,

e)      Passengers must be briefed not to use the affected door,

f)      All passenger seats halfway to the next exit in each direction from the inoperative door, across the entire width of the airplane, shall be blocked off with conspicuous tapes or ropes that contrast with the interior prior to loading passengers. Only the seats in these areas shall be blocked; main passenger aisles, cross aisles, and exit areas must not be blocked. (For an inoperative forward door/ slide, the blocked seating area shall extend from the forward cabin end, rearward to a line halfway between the inoperative forward door and the next set of doors aft of the inoperative one. For an inoperative rear door/slide, the blocked seating area shall extend forward from the aft cabin end to a line halfway between the inoperative door and the next set of doors forward of the inoperative one),

g)      Conspicuous signs and placards shall be placed in appropriate locations indicating these seats are not to be occupied by passengers,

 


 

 

 

 

 

 

h)      Seated capacity must not exceed rated capacity of remaining pairs of exits,

i)      For extended range/overwater operations, occupancy shall not exceed the normal rated capacity of the slide/ rafts, or the remaining slide/rafts or the rated overload capacity of the slide/rafts remaining after loss of one additional slide/raft of greatest capacity, whichever is least,

j)      Blocked seating layouts and evacuation procedures must be developed and approved by the FAA certificate holding office for inclusion in the operator’s manual, and

k)      Repairs are made within one flight day.

 

 

 

 

 

 

NOTE 1: Weight and Balance Manifest must be revised as necessary to ensure proper loading limits are observed.

 

 

 

 

 

NOTE 2: Cabin attendants may be stationed in the vicinity of each door within blocked areas.

 

 

 

 

 

NOTE 3: Combination Passenger/Cargo airplanes, main entry doors located in the cargo area may be inoperative with no restrictions.

 

 

 

 

 

 

 

2) All Freighter Configuration

 

 

 

 

 

 

 

 

 

 

 

a) Main Deck Cockpit Configuration

C

-

1

All main entry doors/slides may be inoperative or slide missing except for Crew Entrance Door.

 

 

 

 

 

 

 

b) Upper Deck Cockpit Configuration

C

-

0

Main entry doors/slides located in the cargo area may be inoperative or slide missing with no restrictions.

 

 

 

 

 

 

 

3) All-cargo and Combination Passenger/Cargo Operation

B

-

-

Main entry doors/slides located in the cargo area may be inoperative or slide missing with no restrictions.

 

 

 

 

 

 


 

XX

Upper Deck Escape Slide Inflation System (or Door)

 

 

 

 

 

1) Passenger, Cargo or Mixed (Convertible) Configuration(One Door)

C

1

0

(M)(O)May be inoperative provided only flight crewmembers (including official observers in forward observer seat) occupy the upper deck during takeoff or landing.

 

 

 

 

 

 

 

2) Passenger or Mixed (Combi) Configuration(Two Doors)

 

 

 

 

 

 

 

 

 

 

 

a) Circular Stair

C

2

1

(M) One may be inoperative provided upper deck occupancy is limited to sixteen passengers.

 

APPENDIX "B"

 

MMEL POLICY LETTER 1 (REVISION 1)

 

Inoperative Door and Slide on Wide-Body, Twin-Aisle

Airplanes

 

The following is a description of the number of passengers evacuated for the B-767, B-777, and A300-600 airplane types for certification purposes.  Attached are Passenger Evacuation Summaries showing a comparison of the passengers evacuated through each exit for the manufacturer's certification testing (at maximum seating configuration) and a typical airline seating configuration to provide an indication of the number of passengers expected to deplane through each exit.  The charts showing comparative information is based on ATA data which shows the number of passengers assumed to evacuate through each exit when dispatched with an inoperative door/slide.  The column labeled "Evacuees per Exit" shows the effect of the MMEL restrictions.  The information is provided for the B-767, B-777, and A300-600 airplanes; the B-767 configuration selected for this example has forward and aft Type A doors and Type III exits.

 

The seating restrictions imposed by the MMEL provisos are depicted on the attached airplane interior drawings.  These drawings reflect typical B-767, B-777, and A300-600 airplanes with a mid exit inoperative. The drawings show the MMEL seating limitations imposed by the requirement to restrict seating in an area half the distance between an inoperative and an operative exit.

 

The following information is the fleet experience from Boeing's B-767 database:

 

From the time the B-767 entered service through the end of

1994, the world-wide fleet made 3.948 million departures versus 26 passenger emergency evacuations (fifteen of these evacuations involved acts of sabotage such as bomb threats). Thus, the frequency of emergency passenger evacuations per departure has been approximately 6.6X10-6.  In view of the very onerous operational aspects of using the MMEL door/slide relief and the history of a relatively small ratio of emergency evacuations versus departures, there is little likelihood of an emergency evacuation being conducted with a known inoperative door/slide.

 

In summary, while the MMEL proposal is restrictive, it should provide the basis to gain operational experience which can be used by Flight Operations Evaluation Boards as they approve relief for specific configurations of wide-body, twin-aisle airplanes.

 

767 PASSENGER EVACUATION SUMMARY (A3A CONFIG)

CERTIFICATION ANALYSIS

 

 

DEMONSTRATED EVACUEES FOR CERTIFICATION

TOTAL EVACUATED FOR CERTIFICATION

EXIT DESIGN LIMIT

EXITS

EXIT INOP

1

2

3

NONE

110

38

107

255

255

1

X

38

107

145

145

2

110

X

107

217

220

3

110

38

X

148

145

 

OPERATIONAL ANALYSIS

 

EFFECT OF PROPOSED MMEL SEATING RESTRICTION
 "HALF THE DISTANCE" OR "RATED CAPACITY"

MAXIMUM CERTIFIED CONFIG (255 PAX)

TYPICAL OPERATOR CONFIG (201 PAX)

EXIT INOP

BLOCKED SEATS

OCCUPIED SEATS

EVACUEES PER EXIT

BLOCKED SEATS

OCCUPIED SEATS

EVACUEES PER EXIT

NONE

0

255

42.5

0

201

33.5

1

51

145

29.0

35

145

59.0

2

143

112

22.4

114

87

17.4

3

61

145

29.0

52

145

29.0

 

 


 

777 PASSENGER EVACUATION SUMMARY

CERTIFICATION ANALYSIS

 

 

DEMONSTRATED EVACUEES FOR CERTIFICATION

TOTAL EVACUATED FOR CERTIFICATION

EXIT DESIGN LIMIT

EXITS

EXIT INOP

1

2

3

4

NONE

69

134

117

99

419

440

1

X

134

117

99

350

330

2

69

X

117

99

285

330

3

69

134

X

99

302

330

4

69

134

117

X

320

330

 

OPERATIONAL ANALYSIS

 

EFFECT OF PROPOSED MMEL SEATING RESTRICTION
 "HALF THE DISTANCE" OR "RATED CAPACITY"

MAXIMUM CERTIFIED CONFIG (419 PAX)

TYPICAL OPERATOR CONFIG (292 PAX)

EXIT INOP

BLOCKED SEATS

OCCUPIED SEATS

EVACUEES PER EXIT

BLOCKED SEATS

OCCUPIED SEATS

EVACUEES PER EXIT

NONE

0

419

52.4

0

292

36.5

1

43

330

47.1

12

280

40.0

2

146

273

39.0

72

220

31.4

3

170

249

35.6

152

140

20.0

4

60

330

47.1

56

236

33.7

 


 

A300-600 PASSENGER EVACUATION SUMMARY

CERTIFICATION ANALYSIS

 

 

DEMONSTRATED EVACUEES FOR CERTIFICATION

TOTAL EVACUATED FOR CERTIFICATION

EXIT DESIGN LIMIT

EXITS

EXIT INOP

1

2

3

4

NONE

96

102

67

96

361

375

1

X

102

67

96

265

265

2

96

X

67

96

259

365

3

96

102

X

96

294

330

4

96

102

67

X

265

265

 

OPERATIONAL ANALYSIS

 

EFFECT OF PROPOSED MMEL SEATING RESTRICTION
 "HALF THE DISTANCE" OR "RATED CAPACITY"

MAXIMUM CERTIFIED CONFIG (361 PAX)

TYPICAL OPERATOR CONFIG (267 PAX)

EXIT INOP

BLOCKED SEATS

OCCUPIED SEATS

EVACUEES PER EXIT

BLOCKED SEATS

OCCUPIED SEATS

EVACUEES PER EXIT

NONE

0

361

45.1

0

267

33.4

1

34

265

37.9

16

251

35.9

2

138

223

31.9

97

170

24.3

3

158

203

29.0

124

143

20.4

4

49

265

37.9

44

223

31.9

 

 

APPENDIX C

 

Safety Issues

 

In review of this proposal there is the realization of the 20 years of safe service experience by U.S. and foreign air carriers where no accidents or incidents occurred on flight when it was necessary to operate with an inoperative door or slide to a point where repairs could be made.  This points to the very remote probability that an emergency evacuation will be necessary at a time when a flight is operated with an inoperative door/slide.  Service experience has been accumulated on airplanes such as the B-747, L-1011, DC-10, MD-11, and the original Airbus A300 where MMEL door/slide relief is presently authorized.  There is every reason to expect that this safe service experience will continue with the new airplanes proposed for similar type relief.

 

Passenger evacuation summaries (Appendix B) for the B-767, B-777, and A300-600 show that because of the severe reduction in the number of passengers that may be carried with a door/slide inoperative, the risk in a passenger evacuation, is minimized because of the fewer passengers that need to exit the other available door/slide exits.

 

The following is an example of the case of a B-777 with a typical operator configuration of 292 passengers.  The exit design criteria of each door on the B-777 is 110 evacuees in a 90-second time period.  With a typical operator configuration seating 292 passengers, 8 exits are available which averages 36.5 passenger evacuees per exit.

 

Assuming number 3L door/slide is inoperative, the MMEL would impose a seating restriction of "half the distance or "related capacity" which translates to 152 blocked seats and 140 occupied seats.  This situation leaves 7 exits available to evacuate 140 passengers in the event of an emergency evacuation which would result in 20-passenger evacuees per exit as opposed to 36.6-passenger evacuees per exit with all 8 exits available for 292 passengers.  Therefore, safety is not an issue since a lessor number of passengers (20) would be required to exit at each operable door as opposed to 36.5 passengers for each door with a typical operator 292-passenger configuration.